PICTORIAL 

PHOTOGRAPHY 

ITS  PRINCIPLES 
AND  PRACTICE 


PAUL  L.  ANDERSON 


V 


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ITS  PRINCIPLES  AND  PRACTICE 


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PUBLISHERS  PHILADELPHIA 


PICTORIAL  PHOTOGRAPHY 

ITS  PRINCIPLES  AND  PRACTICE 


BY 

PAUL  L.  ANDERSON,  E.E. 

LECTURER,  THE  CLARENCE  H.  WHITE  SCHOOL  OF  PHOTOGRAPHY 


WITH  23  ILLUSTRATIONS  AND  35  DIAGRAMS 


PHILADELPHIA  AND  LONDON 

J.  B.  LIPPINCOTT  COMPANY 


COPYRIGHT,  1917,  BY  J.  B.  LIPPINCOTT  COMPANY 


PUBLISHED  JULY,  1917 


PRINTED  BY  J.  B.  LIPPINCOTT  COMPANY 
AT  THE  WASHINGTON  SQUARE  PRESS 
PHILADELPHIA,  U.  S.  A. 


THE  GETTY  RESEARCH 


THIS  BOOK  IS  AFFECTIONATELY  INSCRIBED  TO  MY 
MOTHER  AND  MY  WIFE,  SINCE,  BUT  FOR  THEIR 
ENCOURAGEMENT  AND  ASSISTANCE,  IT  WOULD 
IN  ALL  PROBABILITY  NOT  HAVE  BEEN  WRITTEN 


FOREWORD 


In  preparing  the  discussion  of  the  technique  of  pic- 
torial photography  which  is  given  in  the  following  pages 
the  author’s  purpose  has  been  to  produce  a book  adapted 
to  the  needs  of  those  workers  who,  without  wishing  to 
undertake  a study  of  the  abstruse  scientific  phases  of 
the  art,  nevertheless  have  passed  beyond  the  element- 
ary stages  and  feel  a desire  for  pictorial  expression. 
Every  effort  has  been  made  to  adapt  the  book  to  the 
needs  of  such  photographers,  and  for  that  reason  the 
author  has  endeavored  to  make  clear,  not  only  the  ac- 
tual technical  methods,  but  also  the  fundamental  prin- 
ciples underlying  those  methods,  since  a thorough  grasp 
of  the  principles  is  of  importance  in  enabling  the  worker 
to  locate  and  to  correct  his  mistakes  and  also  to  study 
and  to  grow  in  power  of  expression,  which  is  almost 
impossible  when  his  knowledge  is  simply  a matter  of 
remembering  certain  arbitrary  facts. 

Inasmuch  as  pictorial  photography  only  is  being 
dealt  with,  some  subjects  which  would  otherwise  find  a 
place  in  a text-book  have  not  been  discussed,  the  most 
conspicuous  omission  of  this  sort  being  in  the  case  of 
gas-light  papers,  which,  though  valuable  to  the  com- 
mercial worker,  have  not  great  usefulness  to  the  pic- 
torialist,  because  of  their  lack  of  absolute  permanence 
and  of  the  highest  esthetic  quality.  The  author  has 
regretfully  been  obliged  to  omit  a discussion  of  ozotype 
and  of  ozobrome,  owing  to  the  difficulty  of  obtaining 
the  materials  for  these  processes  in  this  country.  How- 

7 


FOREWORD 


ever,  the  author  has  in  his  own  work  given  especial 
attention  to  the  various  printing  processes  which  are  of 
value  to  the  pictorial  worker,  and  feels  that  the  discus- 
sion of  these  mediums  is  satisfactorily  complete.  Atten- 
tion is  called  in  particular  to  the  discussion  of  the  color 
sensitiveness  of  plates,  since  the  author’s  experience, 
both  as  photographer  and  as  teacher,  leads  him  to  be- 
lieve that  a fuller  understanding  of  the  principles  of 
orthochromatics  inevitably  results  in  an  improvement 
from  the  pictorial  standpoint. 

It  has  seemed  well  to  include  examples  of  the  work 
of  noted  photographers,  for  the  sight  of  such  work  is  a 
more  powerful  stimulus  and  incentive  than  any  amount 
of  verbal  discussion. 

The  author’s  thanks  are  due  to  the  Eastman  Kodak 
Company  and  to  the  International  Photo  Sales  Cor- 
poration for  permission  to  reproduce  illustrations  from 
their  catalogues;  to  Dr.  C.  E.  K.  Mees,  of  the  Eastman 
Kodak  Company,  for  permission  to  quote,  in  Chapter 
III,  from  his  book,  “ Orthochromatic  Filters”;  to  Mr. 
W.  R.  Latimer,  for  the  comparative  photographs  of  a 
colored  test  chart,  in  the  same  chapter,  and  for  the  val- 
uable experimental  work  on  carbon  tissues,  embodied  in 
the  table  in  Chapter  XI;  to  Mr.  Charles  Kendall,  for 
suggestions  concerning  the  transferring  of  oil  and  brom- 
oil  prints;  and  to  the  photographers  who  have  so  kindly 
furnished  prints  for  illustration 

The  author  hopes  that  these  pages,  the  result  of 
several  years  of  study  and  experiment,  may  prove  of 
value  to  his  readers,  and  may  help  them  to  a fuller 
expression  of  their  artistic  desires. 


East  Orange,  N J.,  1917 
8 


Paul  L.  Anderson 


CONTENTS 


PART  I— APPARATUS 

CHAPTER  PAGE 

I.  THE  CAMERA  17 

Function — Adjustments — Types 

II.  THE  LENS  24 


Wave  Theory  of  Light — Refraction  of  Light — 
Formation  of  the  Image — Focal  Length  of  a 
Lens — Dispersion  of  Light — Chromatic  Aberra- 
tion— Spherical  Aberration — Curvature  of  the 
Field — Flare — Distortion — Astigmatism — Types 
of  Lens — Diaphragms — Depth  of  Field  and 
Depth  of  Focus — Diaphragm  Markings — Speeds 
of  Lenses — Focal  Length  and  Perspective — The 
Pin-hole — Discussion  of  the  Soft  Focus  Lens. 

III.  PLATES— FILMS— RAY-FILTERS  57 

The  S p e c t r u m — Test  Chart — Photographing 
Without  a Ray-filter — The  Ray-filter — Hala- 
tion— Bromide  Paper — Plates  or  Films. 

IV.  EXPOSURE  AND  DEVELOPMENT 77 

Characteristic  Curve  of  Plate — Hurter  and 
Driffield’s  Law — Failure  of  Hurter  and  Drif- 
field’s Law — Treatment  of  Under-  and  Over- 
exposure— Characteristics  of  Abnormal  Nega- 
tives— Function  and  Composition  of  the  De- 
veloper— Methods  of  Development — Character- 
istics of  Various  Developers. 

V.  MISCELLANEOUS  APPARATUS  92 

Actinometers  and  Exposure  Tables — Shutters — 
Other  Apparatus. 


9 


CONTENTS 


PART  II.— NEGATIVE  MODIFICATIONS 

VI.  MANIPULATION  OF  NEGATIVES  101 

Manipulation  of  the  Negative — Intensifica- 
tion— Reduction — Retouching  on  the  Film — 
Retouching  on  the  Back — Combination  Print- 
ing. 


VII.  ENLARGING  115 

Reasons  for  Enlarging — 'Reasons  for  Making 
Enlarged  Negatives — Enlarging  Methods  and 
Apparatus — Daylight  and  Artificial  Light — 
Glass  or  Paper  Negatives — Technique  of  En- 
larging— Bromide  Enlarging. 


PART  III.— PRINTING  METHODS 

VIII.  THE  IDEAL  MEDIUM 133 

Permanence — Rendering  of  Gradations — Tex- 
ture— Modifications  of  Color — Modifications 
of  Relative  Values — Modifications  of  Total 
Contrast — Convenience — Duplication. 


IX.  DISCUSSION  OF  VARIOUS  MEDIUMS  138 

Platinum,  Commercial — Platinum,  Hand-sensi- 
tized — Carbon  — Gum  — Gum  Platinum  — Oil — 
Bromoil — Oil  and  Bromoil  Transfer — Photo- 
gravure. 


X.  TECHNIQUE  OF  PLATINUM  144 

The  Negative  — Printing  — Development  — Less 
Contrast — More  Contrast — Warmer  Tones — 
Colder  Tones — Old  Paper — General  Remarks — 
Hand-sensitized  Platinum. 


10 


CONTENTS 


XI.  TECHNIQUE  OF  CARBON  160 

Theory — The  Tissue — Sensitizing  by  Immer- 
sion— Bichromate  Poisoning — Quick-drying  Sen- 
sitizer— Printing — Need  for  Transferring — 
Making  Transfer  Paper — Transferring — Strip- 
ping — Development  — Local  Modifications  — 
Multiple  Printing — Registration — Failures — 
General  Remarks — Speed  and  Scale  of  Carbon 
Tissues. 


XII.  TECHNIQUE  OF  GUM  181 

Theory — Materials  Required — Sizing — The  Coat- 
ing Mixture — Coating  the  Paper — Printing — 
Development — Multiple  Printing — The  Actin- 
ometer — Failures. 


XIII.  TECHNIQUE  OF  GUM-PLATINUM 


206 


XIV.  TECHNIQUE  OF  OIL  AND  BROMOIL  AND  OF 

TRANSFERRING  211 

Theory  of  Oil — Theory  of  Bromoil — Theory  of 
Transferring  — Materials  Required  — Sensitiz- 
ing— Printing — Soaking — Inking — Drying  and 

Degreasing — General  Remarks — Bromoil — The 
Negative — The  Bromide  Print — Bleaching — Sub- 
sequent Treatment — Transferring. 


XV.  TECHNIQUE  OF  PHOTOGRAVURE  231 

Theory  — The  Copper  Plate  — Laying  the 
Ground — The  Positive — The  Resist — Etching 
the  Plate — Printing — Modifications. 


11 


CONTENTS 


PART  IV.— COLOR 

XVI.  DESIRABILITY  OF  COLOR  IN  PHOTOGRAPHY  ....  251 

XVII.  THE  TECHNIQUE  OF  COLOR  PHOTOGRAPHY 256 

The  Autochrome  Process — The  Paget  Process — 

The  Hess-Ives  Process  — Three-color  Gum  — 
Multi-color  Gum  Printing. 

PART  V.— MISCELLANEOUS 

XVIII.  PHOTOGRAPHY  BY  ARTIFICIAL  LIGHT  273 

The  Mercury-vapor  Arc — Incandescent  Gas — 
Flash-light — Other  Illuminants. 

XIX.  MOTION  PICTURE  PHOTOGRAPHY  278 

Exposure  — Development — Drying  — Printing — 
Toning  the  Positive — General  Remarks. 

XX.  CONCLUSION  292 


12 


ILLUSTRATIONS 

EXAMPLES  OF  PICTORIAL  PHOTOGRAPHY 

Portrait  of  Henry  R.  Poore.  (From  a carbon  print) ..  Frontispiece 
By  Paul  L.  Anderson 

Blessed  Art  Thou  Among  Women.  (From  a platinum  print)  ....  24 

By  Gertrude  Kasebier  / 

The  Cave.  (From  a platinum  print) 56 

By  Clarence  H.  White 

Landscape.  (From  a platinum  print) 82 

By  Karl  Struss 

The  Dance.  (From  a platinum  print) 108 

By  Edward  R.  Dickson 

Capri.  (From  a bromide  enlargement) 128 

By  Karl  Struss 

The  Stygian  Shore.  (From  a carbon  print) 162 

By  H.  Y.  Summons 

The  Driving  Wind.  (From  a gum  platinum  print) 190 

By  Paul  L.  Anderson 

The  Driving  Wind.  (From  an  oil  print) 212 

By  Paul  L.  Anderson 

A Sign  Shadow,  Chester.  (From  a bromoil  transfer) 230 

By  Charles  Kendall 

The  Connecticut  River.  (From  a platinum  print) 262 

By  W.  E.  Macnaughton 

INSTRUMENTS  AND  PROCESSES 

Box  Camera 20 

Folding  Film  Camera 21 

Sectional  Illustration  Showing  Principle  of  Reflecting 

Camera.  22 

Folding  Hand  Camera 22 

View  Camera 22 

Studio  Camera 22 

Miniature  Camera 23 

Copies  of  Color  Chart  with  Various  Plate  and  Filter  Com- 
binations   60 

Portrait  Taken  on  Ordinary  Plate 64 

Portrait  Taken  on  Panchromatic  Plate  with  fully  Correcting 

Filter  64 

Exterior  of  Motion  Picture  Camera 278 

Mechanism  of  Motion  Picture  Camera 278 


13 


PART  I 
APPARATUS 


PICTORIAL  PHOTOGRAPHY 
ITS  PRINCIPLES  AND  PRACTICE 


CHAPTER  I 
THE  CAMERA 

Function. — Fundamentally,  the  camera  is  nothing 
more  than  a light-tight  box,  having  an  arrangement  for 
holding  a light-sensitive  substance  (plate  or  film)  and  a 
device  (lens  or  pin-hole)  for  projecting  on  this  sensitive 
substance  an  image  of  objects  external  to  the  camera. 
Some  of  the  simpler  cameras  approximate  closely  to 
this  elementary  form,  but  in  practice  other  adjustments 
are  usually  added,  either  to  make  possible  work  which 
could  not  be  done  with  the  fundamental  type,  or  to 
facilitate  work  of  one  kind  or  another.  Some  adjust- 
ments and  characteristics  are  incompatible  with  others, 
so  the  design  of  the  camera  must  always  be  in  the 
nature  of  a compromise,  and  the  instrument  should  be 
chosen  with  regard  to  the  purpose  for  which  it  is  desired. 

Adjustments. — The  ideal  camera  would  possess  the 
following  adjustments  and  characteristics: 

A folding  bellows , operated  by  rack  and  pinion,  with 
an  arrangement  for  locking  at  any  desired  extension, 
and  a maximum  draw  of  not  less  than  twice  the  focal 
length  of  the  lens  to  be  employed.  (For  focal  length  of 
lens  see  Chapter  II.)  As  will  be  seen  later,  the  farther 
the  object  is  from  the  camera  the  less  the  bellows 
extension  necessary,  and  the  closer  it  is  the  farther  the 
2 17 


THE  CAMERA 


lens  must  be  from  the  plate  in  order  to  focus  on  it,  a 
maximum  extension  of  twice  the  focal  length  of  the 
lens  permitting  of  making  the  image  the  same  size  as 
the  original,  this  being  about  the  limit  that  is  usually 
desired,  except  for  special  work,  such  as  reproduction. 

Rising  and  Falling  Front. — That  is,  a device  whereby 
the  lens  may  be  raised  without  the  necessity  of  tilting 
the  camera.  This  is  useful  in  raising  or  lowering  the 
image  on  the  plate,  as  is  indicated  in  Figure  1. 

Traversing  (or  Sliding)  Front. — This  is  an  arrange- 
ment whereby  the  lens  may  be  moved  back  and  forth 


across  the  bed  of  the  camera.  The  purpose  is  apparent 
from  Figure  1. 

Swing-bach. — This  is  a device  by  means  of  which  the 
back  of  the  camera,  together  with  the  plate,  may  be 
swung  through  a small  arc  about  either  a horizontal  or 
a vertical  axis.  The  swing  about  a horizontal  axis  is 
the  more  important,  and  for  pictorial  work  should  never 
be  omitted,  the  other  swing  being  desirable  but  not 
imperative.  A swing  front,  permitting  of  tilting  the 
lens,  serves  the  same  purpose,  and  is  sometimes  fur- 
nished. Whether  the  swing  is  of  the  back  or  of  the 
front,  it  should  preferably  be  actuated  by  rack  and 
pinion,  and  be  capable  of  locking  at  any  desired  point. 

18 


ADJUSTMENTS 


The  function  of  the  swing-back  is  two-fold.  In  the 
first  place,  as  stated  above,  the  lens  must  be  farther 
from  the  plate  to  focus  on  nearby  objects  than  when  the 
objects  are  more  distant.  Hence  it  follows  that,  say, 
in  landscape  work,  it  will  be  impossible  to  focus  (at 
full  aperture  of  the  lens)  on  both  foreground  and  dis- 
tance simultaneously  if  the  plate  is  at  right  angles  to 
the  axis  of  the  lens.  By  swinging  the  top  of  the  plate 
(since  the  image  is  inverted)  farther  from  the  lens  the 
foreground  and  distance  may  be  brought  into  focus  at 
the  same  time  without  the  necessity  for  using  a small 
diaphragm  in  the  lens  (see  Figure  2).  In  the  second 


place,  if  we  are  photographing  a tall  object  and  find  it 
necessary  to  tilt  the  camera  in  order  to  include  the 
desired  amount,  parallel  vertical  lines  will  converge  in 
the  negative.  If,  however,  the  back  be  swung  so  as  to 
remain  parallel  to  the  plane  of  the  object  (that  is, 
vertical)  this  effect  will  not  appear.  This  is  not  of 
much  consequence  in  landscape  work,  where  we  rarely 
find  parallel  lines,  but  is  of  primary  importance  in 
architectural  photography. 

Rotating  ( Usually  Called  Revolving)  Back. — This  per- 
mits of  arranging  the  plate  with  the  long  axis  either 
vertical  or  horizontal  as  may  be  desired,  without  the 
necessity  of  turning  the  camera  on  its  side.  It  is  some- 


THE  CAMERA 


times  furnished  as  a reversible  back,  which  must  be 
detached  from  the  camera  in  order  to  turn  it,  and  this 
form  is  quite  as  desirable  as  the  other. 

In  addition,  the  camera  should  be  so  designed  and 
constructed  as  to  be  perfectly  rigid  when  fully  extended, 
should  be  strong  enough  to  withstand  ordinary  use, 
and  should  be  light  and  capable  of  being  folded  into  a 
small  space  for  transportation.  For  pictorial  work  it  is 
also  important  that  the  front-board  be  large,  since 
lenses  of  large  aperture  and  comparatively  great  focal 
length  will  ordinarily  be  employed.  Finally,  it  is 
strongly  recommended  that  the  student  begin  with  a 
camera  having  a ground  glass,  since  practice  in  arrang- 
ing the  picture  is  of  inestimable  value  in  the  study  of 
composition,  and  a view-finder  is  too  small  to  make 
such  practice  possible.  The  miniature  cameras,  as  well 
as  the  folding  film  type,  valuable  as  they  are  to  more 
experienced  workers,  cannot  be  considered  desirable  for 
beginners.  In  order  to  facilitate  practice  in  composition, 
and  also  because  a large  print  is  undeniably  more  impres- 
sive than  a small  one,  it  is  advised  that  the  camera  be  as 
large  as  the  student’s  strength  will  permit  him  to  carry, 
and  it  will  in  general  be  found  that  8 X 10  is  about  the  limit 
in  this  regard  for  a man,  and  6}^X 8^  for  a woman. 

Types. — Box  Type. — This  is  illustrated  in  Figure  3, 
and  consists  simply  of  a box  having  a lens  (usually  a 
single  achromatic)  in  front,  with  a simple  type  of 
shutter,  and  a device  for  winding  a roll  of  film  so  that 
successive  portions  are  exposed  to  the  image  projected 
by  the  lens.  Sometimes  a film  pack  is  used  instead  of 
a roll  film,  but  the  instrument  is  of  the  simplest,  and 
need  not  be  seriously  considered  here.  True,  good 

20 


By  courtesy  of  The  Eastman  Kodak  Company 

FIG.  3— BOX  CAMERA 


By  courtesy  of  The  Eastman  Kodak  Company 

FIG.  4.— FOLDING  FILM  CAMERA 


TYPES 


work  has  been  done  with  such  cameras,  but  only  under 
the  most  favorable  circumstances. 

Folding  Film  Type. — This  next  higher  development 
of  the  camera  (Figure  4)  adds  the  extensible  bellows, 
the  rising  and  falling  front  (as  a rule)  and  ordinarily 
has  a rapid  rectilinear  lens,  though  the  objective  is 
sometimes  a single  achromatic  and  sometimes  an  an- 
astigmat.  The  shutter  is  more  complete  in  its  adjust- 
ments than  that  of  the  box  type,  and  may,  in  fact,  be 
the  highest  type  of  between-lens  shutter.  In  some  cases 
the  focal  plane  shutter  is  used,  and,  in  general,  this  type 
of  camera  may  be  considered  the  best  form  of  snap- 
shot instrument  except  the  reflex.  The  folding  film 
camera,  however,  lacks  the  large  front-board,  the  long 
bellows  extension,  the  swing-back,  and,  as  a rule,  the 
focussing  screen,  so  it  cannot  be  considered  a desirable 
instrument  for  the  pictorial  worker,  being,  in  fact, 
designed  for  record  work  when  compactness  and  porta- 
bility are  of  importance.  It  is,  however,  possible  to 
secure  ground  glass  attachments  for  most  cameras  of 
this  type,  thus  extending  their  usefulness. 

Reflex  Type. — This  camera  is  the  best  for  snap-shot 
and  high-speed  work,  and  the  writer’s  experience,  as 
well  as  that  of  many  well-known  workers,  indicates 
that  it  may  be  very  useful  to  the  photographer  whose 
aim  is  purely  pictorial,  some  artists  even  going  so  far 
as  to  discard  all  other  types  in  favor  of  this  one.  As 
shown  in  Figure  5,  a mirror  is  hinged  at  an  angle  of 
45°  to  the  axis  of  the  lens,  the  image  being  projected  on 
the  mirror  and  reflected  by  it  on  a horizontal  ground 
glass,  where  it  may  be  examined  by  looking  down  into 
the  hood.  Pressing  a lever  at  the  side  of  the  camera 

21 


By  courtesy  of  The  Eastman  Kodak  Company 

FIG.  6— FOLDING  HAND  CAMERA 


By  courtesy  of  The  Eastman  Kodak  Company 

FIG.  7.— VIEW  CAMERA 


By  courtesy  of  The  Eastman  Kodak  Company 

FIG.  8.— STUDIO  CAMERA 


By  courtesy  of  the  International  Photo  Sales  Corporation 
FIG.  9.— MINIATURE  CAMERA 


TYPES 


rendering  it  unavailable  for  landscape  and  genre 
work,  as  well  as  for  home  portraiture. 

The  Miniature  Type . — There  are  many  designs  of 
this  camera,  one  of  which  is  shown  in  Figure  9,  such 
instruments  generally  having  high  grade  lenses  and 
shutters,  but  being  designed  with  a view  to  extreme 
portability.  They  are  light, and  compact,  and  are  there- 
fore exceedingly  desirable  for  record  work,  especially 
when  travelling,  but  are  not  to  be  recommended  to  the 
pictorial  worker  unless  he  has  had  a good  deal  of  ex- 
perience with  a camera  having  a focussing  screen,  in 
which  case  they  may  be  very  valuable. 

As  already  indicated,  the  writer  would  advise  that 
the  student  begin  with  a view  camera  or  (if  cost  is  not 
important)  one  of  the  folding  hand  type,  8X10  or 
034X8 x/l,  and  when  experience  in  composition  has  been 
gained  procure  in  addition  one  of  the  reflex  type,  4X5 
or  334X434?  since  the  latter,  being  more  portable  and 
easily  operated,  will  often  be  of  use  when  the  larger 
camera  would  have  to  be  left  at  home.  In  addition, 
the  reflex  will  be  found  of  great  value  when  photo- 
graphing children,  no  other  camera  being  comparable 
with  it  for  this  purpose. 

There  are  many  different  makes  of  each  of  these 
types,  but  so  far  as  the  writer  knows  there  is  none 
which  cannot  be  recommended  as  regards  construction. 
The  camera  should,  except  in  the  case  of  the  box,  fold- 
ing film,  or  miniature  type,  be  purchased  without  a 
lens,  since  the  manufacturers  almost  invariably  fit  lenses 
of  too  short  focal  length  for  pictorial  work,  and  do  not 
furnish  objectives  of  the  type  most  useful  to  the  artist 
except  on  special  order. 


CHAPTER  II 


THE  LENS 

Wave  Theory  of  Light. — If  we  stand  beside  a 
pond  of  still  water  and  throw  a stone  into  it  we  shall 
see  a series  of  waves  passing  out  in  concentric  circles 
from  the  center  of  disturbance.  If  there  be  a chip  or  a 
leaf  floating  on  the  surface  it  will  be  apparent,  on  watch- 
ing this  object,  that  there  is  no  forward  motion  of  the 
water  itself  (unless  the  stone  be  so  large  relatively  to 
the  pond  as  to  cause  a marked  displacement  of  the 
water)  but  that  the  individual  molecules  simply  rise 
and  fall  in  a vertical  direction,  each  communicating 
its  motion  to  the  next,  so  that  the  wave  travels  for- 
ward. The  accepted  theory  regards  the  propagation 
of  light  as  being  due  to  a similar  wave  motion  in  the 
luminiferous  ether,  an  invisible,  imponderable  sub- 
stance pervading  all  matter,  the  wave  motion  originat- 
ing in  any  self-luminous  body.1  The  motion  of 
water  particles  is  represented  diagrammatically  in 
Figure  10,  which  shows  two  complete  waves,  but  it 
must  be  understood  that  whereas  the  water  particles 
vibrate  only  vertically,2  at  right  angles  to  the  axis  of 
translation  of  the  wave,  the  ether  particles  vibrate  at 
right  angles  to  this  direction,  and  in  all  azimuths  to  it, 
that  is,  vertically,  horizontally,  obliquely,  etc.  The 

1 One  theory  regards  the  propagation  of  light  as  consisting  of  a 
series  of  irregular  pulses  which  are  transformed  into  a simple  harmonic 
motion  on  encountering  any  material  obstacle,  but  since  we  are  dealing 
with  light  only  after  it  has  encountered  such  obstacles  the  above  statement 
may  be  taken  as  correct. 

* Actually,  in  small  vertical  circles. 

24 


BLESSED  ART  THOU  AMONG  WOMEN 
BY  GERTRUDE  KASEBIER 
From  a Platinum  Print 


REFRACTION  OF  LIGHT 


distance,  A — B,  from  the  crest  of  one  wave  to  that  of 
the  next,  or,  more  generally,  from  any  point  in  a wave 
to  the  point  which  is  in  the  same  phase  in  the  next 
wave,  is  known  as  the  wave  length.  Unless  artificially 
deflected,  light  tends  to  travel  in  straight  lines,  but 
it  may  be  reflected  or  refracted,  that  is,  bent,  and  it 
is  upon  this  principle  of  refraction  that  the  action  of 
a lens  depends. 

Refraction  of  Light. — Consider  now  the  case  of  a 
ray  of  light,  travelling  in  a straight  line,  and  encountering 
a plane,  parallel-sided  sheet  of  glass.  If  the  ray  meets 
the  glass  normally  it  will  simply  be  retarded,  since  light 
travels  more  slowly  in  a dense  medium  than  in  a rarer 


one,  but  if  it  meets  the  glass  at  any  angle  other  than  a 
right  one  the  edge  which  first  reaches  the  glass  is  re- 
tarded more  than  the  other,  since  the  latter  is  still 
travelling  in  air.  On  emerging  from  the  glass  the 
reverse  takes  place,  and  the  ray  resumes  its  former 
direction,  having  merely  been  displaced  laterally 
(Figure  ll).  If,  however,  the  faces  of  the  glass  are  not 
parallel,  the  ray  is  refracted  differently,  as  shown  in 
Figure  12,  where  a prism  of  glass  is  represented.  Here 
the  edge  B — B'  is  retarded  less  than  the  edge  A — A', 
so  that  the  ray  is  bent  toward  the  base  of  the  prism, 
and  if  sufficiently  produced  will  meet  the  produced  base 
at  some  point,  the  distance  of  this  point  from  the  prism 

25 


THE  LENS 


depending  on  the  angle  of  the  prism,  the  kind  of  glass 
of  which  it  is  made,3  and  the  angle  at  which  the  incident 
ray  meets  the  prism. 


of  the  glass,  and  the  refractive  index  is  defined  as  follows.  If  we  measure 
the  angle,  I,  which  a ray  of  light  incident  upon  a transparent  plane  surface 


makes  with  the  normal  to  the  surface,  and  the  angle,  I',  which  the  ray 
makes  with  the  normal  after  refraction,  it  will  be  found  that  the  ratio  of 
the  sines  of  these  angles  is  constant  for  a given  substance.  This  ratio, 

-s|n-T/-is  called  the  refractive  index  of  the  substance. 

SID  V 

26 


REFRACTION  OF  LIGHT 


Every  point  of  every  natural  object  sends  out  rays 
of  light  in  all  directions,  either  originating  in  the  object 
or  reflected  by  it,  and  in  ordinary  photographic  work 
those  rays  which  reach  the  lens  may  * be  considered 
parallel,  since  the  diameter  of  the  lens  is  usually  small 
compared  to  the  distance  which  the  rays  travel  before 
reaching  it.  If,  now,  two  prisms  be  placed  with  their 
bases  together,  as  in  Figure  14,  the  two  rays,  if  equi- 
distant from  the  axis,  will  obviously  meet  on  the  other 
side  of  the  prisms,  and  will  form  an  image  of  the  point 


Fig.  14. 


from  which  they  come.  Since  a spherical  surface  (the 
only  kind  which  can  be  accurately  ground  except  at  a 
prohibitive  expense)  may  be  considered  as  made  up  of 
an  infinite  number  of  triangles,  it  follows  that  all  rays 
of  light  emanating  from  a point  and  falling  on  a lens 
will  be  converged  by  the  lens  and  will  form  an  image 
of  the  point  from  which  they  come,  and  this  is  the 
case  for  all  points  of  the  object,  the  sum  of  the  images 
of  the  points  constituting  an  image  of  the  object.  Since 
the  degree  of  refraction  is  a fixed  function  of  the  quality 

27 


THE  LENS 


of  the  glass  and  the  curvature  of  the  surface,  it  follows 
that  rays  meeting  the  lens  at  a more  acute  angle  than 
others  will  emerge  at  a more  obtuse  one,  this  being  the 
reason  for  the  necessity  for  setting  the  ground  glass 


Fig.  15. 


farther  from  the  lens  when  focussing  on  a near  object 
than  when  focussing  on  a more  distant  one.  A con- 
sideration of  Figure  15  will  make  this  clear. 

; Formation  of  the  Image. — We  have  seen  that  a lens 
forms  an  image  of  an  object  placed  in  front  of  it,  but 
for  the  sake  of  clearness  this  is  illustrated  in  Figure  16, 


Fig.  16. 


where  two  rays  from  each  of  two  points  are  considered. 
This  also  indicates  the  reason  for  the  inversion  of  the 
image  on  the  ground  glass. 

Focal  Length  of  a Lens. — The  focal  length  (often 

28 


«CP. 


FOCAL  LENGTH  OF  A LENS 


incorrectly  called  focus)  of  a lens  is  the  distance  from 
the  lens  to  the  point  at  which  rays  originally  parallel 
meet  after  refraction,  this  definition  being  of  im- 
portance.4 The  focal  length  is  illustrated  in  Figure  17, 
and  depends  on  the  design  of  the  lens,  that  is,  the 
curvature  of  the  surfaces  and  the  kind  of  glass  used. 
In  a double  lens,  which  consists  of  two  single  lenses 
mounted  at  opposite  ends  of  a barrel,  the  focal  length 
must  be  measured  from  the  optical  axis  of  the  combi- 
nation, and  this  point  usually  coincides  with  the 


Fig.  17. 


diaphragm,  so  that  the  focal  length  may  be  measured 
from  this  point,  the  determination  in  this  manner  being 
sufficiently  accurate  for  practical  purposes.  To  find 
the  focal  length  of  a lens,  set  the  camera  up  and  focus 
as  sharply  as  possible,  at  full  aperture  of  the  lens,  on 
some  object  more  than  a hundred  feet  away.  Measure 
the  distance  from  the  ground  glass  to  the  lens,  if  a 

4 This  is  not  strictly  correct,  since  it  assumes  that  the  nodal  planes 
coincide  with  the  central  plane  of  the  lens,  which  is  true  only  in  the  case 
of  an  infinitely  thin  lens,  but  for  practical  purposes  it  may  be  considered 
to  be  the  case.  For  a description  of  the  nodal  planes  the  reader  is  referred 
to  “The  Lens,”  by  Bolas  and  Brown,  or  to  “Photographic  Lenses,”  by 
Beck  and  Andrews. 


29 


THE  LENS 


single  lens,  or  to  the  diaphragm,  if  a doublet.  This 
will  be  the  focal  length  of  the  lens,  and  an  error  of  3^  or 
even  inch  will  not  be  of  importance  to  the  pictorialist. 

This  method  is  not  applicable  to  telephoto  lenses. 

Dispersion  of  Light. — If  a ray  of  white  light  be 
allowed  to  fall  on  a prism,  as  in  Figure  18,  it  does  not 
emerge  as  a ray  of  white  light,  but  as  an  elongated 
band  of  different  colors,  thus  proving  that  white  light  is 
a compound.  This  separation  is  known  as  dispersion, 
and  it  has  been  found  to  be  due  to  the  fact  that  white 
light  does  not  consist  merely  of  rays  of  one  definite 


Re.p 

Qree.« 

Violct 


wave  length,  but  is  a synthesis  of  rays  of  many  lengths, 
the  waves  of  different  lengths  being  refracted  differently, 
and  it  has  also  been  found  that  the  rays  of  shorter  wave 
length  are  refracted  more  than  those  of  greater  length. 
Different  portions  of  the  retina  are  sensitive  to  waves  of 
different  lengths,  those  waves  from  4000  to  5000  A.  U.5 
in  length  giving  rise  to  a sensation  of  violet,  those  from 
5000  to  6000  to  one  of  green,  and  those  from  6000  to 
7000  to  one  of  red,  the  mixture  of  these  in  proper 
proportions  causing  a sensation  of  white.6 

5 A.  U.  is  the  abbreviation  for  Angstrom  unit,  the  unit  being  1/10,000,000 
of  a millimeter. 

6 These  figures  are  approximate  only. 

30 


SPHERICAL  ABERRATION 


Chromatic  Aberration. — It  will  be  apparent  that 
a lens  which  analyzes  white  light  cannot  give  a sharp 
image  of  any  point  which  sends  out  rays  that  are  not 
purely  monochromatic,  and  this  defect  is  known  as 
chromatic  aberration,  being  illustrated  in  Figure  19, 
where  the  violet  rays,  being  of  shorter  wave  length 
than  the  green,  are  more  refracted,  and  are  brought 
to  a focus  nearer  the  lens  than  the  latter,  these  in 
turn  being  focussed  nearer  the  lens  than  the  red.  Since 
the  focal  length  of  a lens  depends  fundamentally  on 
the  curvature  of  the  surfaces,  and  the  dispersion  de- 


pends fundamentally  on  the  type  of  glass,  it  follows 
that  by  combining  two  kinds  of  glass  of  different  dis- 
persive powers,  ground  to  different  focal  lengths,  it  is 
possible  to  produce  a lens  which  will  converge  the  rays 
but  will  not  disperse  the  different  wave  lengths,  and 
such  a lens  is  said  to  be  achromatic,  or  free  from  chro- 
matic aberration.  It  should  be  noted  that  no  lens 
which  consists  of  a single  piece  of  glass,  such  as  a 
spectacle  lens,  or  the  Struss  Pictorial  Lens,  can  be 
achromatic. 

Spherical  Aberration. — This  optical  error  is  due 
to  the  fact  that  a lens  having  surfaces  which  are  por- 
tions of  a sphere  converges  the  rays  passing  through 

31 


THE  LENS 


near  the  margins  and  those  passing  through  near  the 
axis  at  different  distances  from  the  lens,  as  is  illustrated 
in  Figure  20.  This  has  nothing  to  do  with  dispersion, 
the  present  error  manifesting  itself  with  monochromatic 
as  well  as  with  compound  light.  Spherical  aberration 
depends  fundamentally  on  the  curvature  of  the  lens 
surface,  and  may  be  either  positive  or  negative,  that  is, 
the  marginal  rays  may  be  brought  to  a focus  either 
nearer  to  or  farther  from  the  lens  than  the  axial.  It  is 
possible  to  grind  lenses  of  the  same  focal  length  in  a 
variety  of  shapes,  and  spherical  aberration  is  corrected 
by  combining  two  lenses  of  different  focal  lengths  in 


which  the  error  is  of  the  same  magnitude  but  opposite 
in  sign,  thus  producing  a lens  which  converges  rays  of 
light  but  has  no  outstanding  spherical  aberration.  It 
should  be  noted  that  if  the  two  surfaces  of  the  lens 
have  different  radii  of  curvature  spherical  aberration  is 
less  when  the  more  deeply  curved  one  (the  one  having 
the  smaller  radius)  is  toward  the  parallel  rays  than  in 
the  reverse  case,  as  is  illustrated  in  Figure  21,  where 
A and  B show  the  same  lens,  turned  in  different  direc- 
tions. Hence,  if  one  of  the  combinations  of  a lens  is 
removed  for  cleaning,  or  if  a single  lens  is  taken  out 
32 


FLARE 


of  the  barrel,  care  must  be  used  to  see  that  it  is  replaced 
in  the  proper  manner. 

Curvature  of  the  Field. — Curvature  of  the  field 
is  that  defect  in  which  the  image  of  a plane  surface  is 
projected,  not  as  a flat  plane,  but  in  a saucer-shaped 
envelope,  the  edges  of  the  image  being  usually  nearer 
the  lens  than  the  center.  Obviously,  if  a lens  has  this 
defect  a flat  plane  cannot  be  brought  to  a focus  on  the 
plate,  for  if  the  center  is  sharp  the  edges  will  be  out  of 
focus,  and  vice  versa.  The  best  approximation  to  a 


Fig.  21. 

focus  is  got  by  setting  the  plate  midway  between  the 
focal  plane  of  the  center  and  that  of  the  edge,  when 
the  diffusion  of  center  and  edge  will  be  only  half  what 
it  would  be  for  either  if  the  other  were  sharply  focussed. 
Curvature  of  the  field  is  corrected  by  designing  the 
lens  so  that  the  focal  length  is  somewhat  greater  for 
the  edges  of  the  field  than  for  the  center. 

Flare. — Flare  is  not,  properly  speaking,  an  in- 
herent optical  defect,  but  is  due  to  faulty  design.  When 
a ray  of  light  passes  from  one  medium  to  another  of 
3 33 


THE  LENS 


different  density  (or,  more  correctly,  of  different  re- 
fractive index)  a portion  of  the  light  is  reflected  from 
the  junction  of  the  two  media.  Hence,  when  light 
falls  on  a lens  part  passes  through  and  part  is  reflected 
from  the  second  surface.  This  last  part  may  be  re- 
flected again  from  the  first  surface  and  again  pass 
through  the  lens,  falling  on  the  plate  at  a point  different 
from  that  where  the  original  ray  falls.  If  these  second- 
ary rays  converge  near  the  plate  we  may  have  a definite 
secondary  image  of  the  originating  point,  this  being 


the  worst  form  of  the  defect,  and  being  called  flare 
spot,  but  if  they  converge  at  a point  remote  from  the 
point  of  convergence  of  the  principal  rays  they  may 
simply  cause  a general  illumination  of  the  plate,  result- 
ing in  slightly  less  brilliant  negatives  than  if  flare  were 
absent.  These  two  conditions  are  illustrated  in  Figure 
22.  It  will  be  apparent  that  an  anastigmat,  which  has 
three  or  five,  or  even  more,  reflecting  surfaces,  will  be 
more  likely  to  show  flare  than  a single  lens,  which  has 
but  one  such  surface,7  and  this  fact  is  of  importance 

7 A cemented  surface  does  not  cause  flare,  since  the  refractive  index  of 
Canada  balsam  (which  is  used  to  cement  the  elements  together)  is  nearly 
that  of  glass. 

34 


DISTORTION 


to  the  pictorialist,  who  does  much  of  his  work  against 
the  light,  flare  being,  of  course,  more  conspicuous  when 
working  in  this  manner  than  when  no  very  brilliant 
light  is  included  in  the  field  of  view. 

Distortion. — Distortion  is  unavoidable  in  a single 
lens,  and  is  that  defect  which  results  in  straight  lines 
near  the  edges  of  the  field  being  rendered  not  as  straight, 


Fig.  23. 


but  as  slightly  bowed.  If  the  diaphragm  is  in  front  of 
the  lens  (that  is,  between  the  lens  and  the  parallel  rays) 
the  bowing  will  be  convex  (barrel-shaped)  as  in  Figure 


Fig.  24. 


23A,  whereas  if  it  is  behind  the  lens  the  distortion  will 
be  concave  (pin-cushion)  as  in  Figure  23B.  The  dotted 
lines  show  the  position  which  the  image  should  have. 

35 


THE  LENS 


Distortion  is  corrected  by  mounting  two  similar  lenses 
at  opposite  ends  of  a barrel,  as  in  Figure  24,  with  the 
diaphragm  symmetrically  placed  between  them,  when 
the  barrel-shaped  distortion  of  the  one  balances  the 
pin-cushion  distortion  of  the  other,  and  such  a lens  is 
known  as  rectilinear.  If  the  combinations  are  not 
similar,  the  diaphragm  is  placed  nearer  one  than  the 
other,  for  the  farther  the  diaphragm  is  from  the  lens, 
the  greater  the  distortion.  Hence,  if  the  combinations 
of  an  asymmetrical  objective  are  removed  from  the 
mount,  care  must  be  taken  to  see  that  they  are  replaced 
in  their  proper  relative  position.  Since  distortion  does 
not  exist  in  lines  coinciding  with  the  axes  of  the  plate, 
and  grows  progressively  worse  toward  the  edges  of 
the  field,  it  follows  that  if  the  lens  has  a focal  length 
which  is  large  relatively  to  the  size  of  the  plate  used, 
so  that  the  plate  occupies  only  a small  portion  of  the 
entire  image  projected  by  the  lens,  distortion  will  not 
be  excessive,  and  in  any  case  it  will  not  appear  unless 
the  picture  includes  straight  lines,  such  as  are  found  in 
architectural  subjects,  so  that  a lens  having  distortion 
may  be  used  with  perfect  satisfaction  for  landscape 
and  portraiture. 

Astigmatism. — Astigmatism  is  that  defect  in  which 
bundles  of  rays  passing  obliquely  through  the  lens  near 
the  margin  are  converged,  not  to  points,  but  to  straight 
lines.  Each  such  bundle  is  converged  to  two  straight 
lines  at  different  distances  from  the  lens  and  at  right 
angles  to  each  other,  or,  rather,  it  is  converged  to  a line, 
and  after  passing  the  point  of  convergence  it  diverges 
again  to  another  line.  Astigmatism  is  difficult  to  illus- 
trate graphically,  but  may  be  understood  by  anyone 

36  . 


TYPES  OF  LENS 


who  will  roll  up  a truncated  cone  of  paper  and  pinch 
the  small  end  to  a straight  line,  afterward  pinching  the 
cone  to  another  straight  line  at  right  angles  to  the  first 
and  at  some  distance  from  the  end.  The  straight  lines 
represent  the  projection  of  a point  of  the  object,  whereas 
if  the  lens  were  free  from  astigmatism  this  projection 
would  be  represented  by  rolling  the  paper  so  as  to  form 
a complete  cone,  the  small  end  being  a true  point.  It 
should  be  noted  that  astigmatism  appears  only  at  the 
margins  of  the  field,  so  will  not  be  noticeable  if  the  lens 
is  of  great  focal  length  relatively  to  the  plate  used. 
The  practical  result  of  astigmatism  is  to  render  it 
impossible  to  focus  simultaneously  on  vertical  and 
horizontal  lines  in  the  same  plane  and  lying  near  the 
edges  of  the  field,  so  that  if  the  image  of  a tree,  for 
instance,  comes  close  to  the  edge  of  the  plate  the  trunk 
will  be  sharp  and  the  branches  blurred,  or  vice  versa , 
but  it  will  not  be  possible  to  get  both  sharp  at  once, 
except  by  using  a small  diaphragm. 

Types  of  Lens. — Spectacle  and  single  meniscus. — 
The  spectacle  lens  is  simply  a double  convex  piece  of 
glass,  such  as  an  ordinary  pocket  magnifying  lens,  and 
the  single  meniscus  is  a concavo-convex  lens  with 
different  radii  of  curvature  for  the  two  surfaces.  There 
is  on  the  market  an  objective  of  the  latter  type,  the 
Struss  Pictorial  Lens,  especially  designed  for  pictorial 
work,  such  a lens  possessing  all  possible  errors,  and 
giving,  as  a result  of  its  optical  defects,  a very  soft  and 
pleasing  quality  of  definition. 

Single  Achromatic. — As  indicated  above,  the  single 
achromatic  lens  consists  of  two  pieces  of  glass  cemented 
together,  and  so  designed  that  the  yellow  (green  + red) 

37 


THE  LENS 


rays  are  brought  to  a focus  at  approximately  the  same 
distance  from  the  lens  as  the  violet,  these  latter  being 
the  most  active  chemically,  whereas  the  yellow  are  the 
most  luminous  to  the  eye.  Such  a lens  is  generally 
partly  corrected  for  spherical  aberration,  and  is  not 
likely  to  show  flare,  but  has  all  the  other  optical  errors. 
In  general  it  gives  somewhat  sharper  definition  than  the 
simpler  types,  but  there  are  a number  of  pictorial  lenses, 
such  as  the  Pink  ham  and  Smith  Semi-Achromatic  and 
Visual  Quality,  the  Wollensak  Verito,  the  Spencer 
Port-Land,  and  others,  in  which  chromatic  aberration 
is  only  partly  corrected,  so  that  a soft  definition  is 
obtained.  It  must  be  understood  that  in  the  objectives 
named,  as  well  as  in  the  Struss  lens,  the  lack  of  correc- 
tion is  intentional,  such  lenses  being  known  as  “soft- 
focus”  or  “pictorial”  lenses. 

Rapid  Rectilinear . — This  objective  consists  of  two 
single  achromatics  mounted  as  shown  in  Figure  24, 
and  is  usually  corrected  for  chromatic  and  spherical 
aberration,  and,  of  course,  for  distortion,  but  has 
curvature  of  the  field  and  astigmatism,  and  is  more 
likely  to  show  flare  than  the  simpler  lenses.  The 
result  of  mounting  two  similar  lenses  in  this  manner 
is  that  the  combination  has  half  the  focal  length  of 
either  of  the  elements,  so  that  if  a long-focus  lens  is 
desired  one  of  the  elements  may  be  removed  from  the 
barrel  and  the  other  used  alone.  This  fact  will  be 
referred  to  later,  in  discussing  diaphragms. 

Anastigmat. — This  is  corrected  for  all  optical  errors, 
but  may  show  flare,  the  writer  having  seen  an  objective 
of  this  type  from  one  of  the  most  favorably  known 
makers  which  possessed  a marked  flare  spot,  and  for 

38 


TYPES  OF  LENS 


this  reason,  if  for  no  other,  would  be  useless  for  pictorial 
work. 

It  must  be  understood  that  it  is  impossible  to  correct 
absolutely  for  any  error,  that  is,  to  make  the  lens  render 
the  image  of  a point  of  light  as  a true  point,  over  the 
entire  field  of  the  objective,  and  an  approximation  is 
all  that  can  be  expected.  The  result  of  any  optical 
error  is  to  make  the  image  of  a point  appear  as  a circle 
of  appreciable  diameter,  and  the  purpose  of  the  designer 
is  to  reduce  the  diameter  of  such  a circle,  known  as  a 
“ circle  of  confusion,”  to  a size  which  will  be  inappre- 
ciable to  the  unaided  eye,  the  ideal  striven  for  being 
usually  1/200  inch.  Further,  this  cannot  be  attained 
over  the  entire  field  of  the  lens,  so  the  designer  endeavors 
to  attain  his  ideal  over  as  large  an  angle  as  pos- 
sible. Hence,  when  a lens  is  said  to  be  corrected 
for  any  fault,  it  means  that  the  circles  of  confusion 
due  to  this  error  do  not  exceed  about  1/200  inch  in 
diameter  over  the  size  plate  for  which  the  lens  is 
listed.  If  used  on  a larger  plate  the  error  will  become 
apparent. 

There  are  other  types  of  lens  than  those  mentioned 
above,  such  as  the  periscopic,  which  consists  of  two 
single  meniscus  lenses  mounted  as  shown  in  Figure  24; 
the  Petzval  portrait  lens,  which  has  great  speed  and 
microscopic  definition  over  a small  angle,  but  has 
little  covering  power,  so  that  the  objective  must  be  of 
great  focal  length  as  compared  to  the  plate;  and  the 
apochromat,  wdiieh  is  the  highest  type  of  anastigmat: 
but  the  first  two  are  seldom  met  nowadays  (except 
that  the  Struss  doublet  is  of  the  periscopic  form)  and 
the  last  is  of  value  only  to  the  process  worker  or  micro- 

39 


THE  LENS 


scopist,  or,  in  general,  to  those  workers  who  require 
extremely  fine  definition. 

So  far  as  definition  is  concerned,  the  objectives 
enumerated  are  arranged  progressively  in  order  of 
increasing  accuracy,  the  single  lenses  giving  the  softest 
drawing  and  the  anastigmat  the  most  exact.  Since  the 
normal  eye  has  chromatic  and  spherical  aberration, 
and  in  many  cases  astigmatism  exists  as  an  abnormality, 
it  follows  that  an  objective  which  gives  microscopic 
definition  cannot  render  objects  as  they  appear  to 
the  observer.  The  pictorialist  generally  wishes  to  rep- 
resent objects  in  this  manner,  so  he  will  do  well  not 
to  select  an  anastigmat,  a rapid  rectilinear,  or  even 
a single  achromatic,  but  to  choose  one  of  the  soft- 
focus  lenses,  since  these,  when  used  wide  open,  give 
a pleasing  quality,  and  may  be  made  to  give  defini- 
tion equal  to  that  of  an  anastigmat  by  the  use  of  a 
small  diaphragm. 

Diaphragms. — It  now  becomes  necessary  to  con- 
sider the  matter  of  diaphragms.  These  are  devices  of 
various  sorts,  so  arranged  that  a portion  of  the  rays 
which  would  ordinarily  pass  through  the  lens  may  be 
excluded,  the  proportion  excluded  depending  on  the 
size  of  the  aperture  in  the  diaphragm.  The  types  of 
diaphragm  are  (1)  rotary,  consisting  of  a metal  plate 
with  circular  holes  of  different  sizes,  so  arranged  that 
by  rotating  the  plate  the  desired  aperture  is  brought  in 
front  of  the  lens;  (2)  Waterhouse,  consisting  of  several 
plates  with  different  sized  holes,  the  desired  plate  being 
slipped  into  a slot  in  the  lens  barrel;  (3)  iris,  consisting 
of  a number  of  thin  curved  plates,  overlapping  and 
arranged  so  that  the  rotation  of  a ring  causes  the  plates 

40 


DEPTH  OF  FIELD  AND  FOCUS 


to  move  toward  a common  center,  thus  diminishing 
the  size  of  the  aperture.  In  single  lenses  the  diaphragm 
is  practically  always  placed  in  front  of  the  glass,  and  in 
compound  lenses  between  the  combinations.  Since 
spherical  aberration  and  astigmatism  are  due  to  the 
marginal  rays  it  follows  that  if  these  rays  are  excluded 
the  errors  disappear,  and  it  will  be  obvious  that  if  only 
the  axial  rays  are  used  in  forming  the  image  these  will 
approach  the  plate  at  a more  acute  angle  than  the 
marginal  rays  (see  Figure  19)  so  that  chromatic  aber- 
ration will  be  less  apparent,  curvature  of  the  field 
being  at  the  same  time  rendered  less  conspicuous  for 
the  same  reason.  Hence,  all  optical  errors  except  dis- 
tortion and  flare  may  be  corrected  by  the  use  of  a small 
stop,8  and  it  follows  that  the  only  advantage  of  the 
anastigmat  is  that  it  gives  fine  definition  at  a larger 
aperture,  and  consequently  wTith  briefer  exposures, 
since  the  more  light  that  passes  through  the  lens,  the 
less  the  time  required  for  it  to  produce  the  desired 
chemical  effect  on  the  plate. 

Depth  of  Field  and  Depth  of  Focus. — If  the 
camera  be  set  up  and  focussed  as  sharply  as  possible 
on  some  object  a short  distance  away  it  will  be  found 
that  objects  slightly  nearer  and  slightly  farther  away 
are  also  in  focus,  so  far  as  can  be  seen  by  the  unaided 
eye.  The  distance  from  the  nearest  to  the  most  remote 
of  the  objects  apparently  sharp  is  known  as  the  depth 
of  field  (often  incorrectly  called  depth  of  focus).  It 
will  also  be  found  that  if  a given  object  is  sharply 

8 There  is  a pseudo  flare  which  results  from  the  reflection  of  light  by 
bright  surfaces  inside  the  lens  barrel,  and  this  may  often  be  diminished  by 
the  use  of  a small  stop.  Obviously,  however,  the  best  way  to  prevent  this 
form  of  flare  is  to  have  the  inside  of  the  barrel  properly  blackened. 

41 


THE  LENS 


focussed  on  it  is  possible  to  move  the  ground  glass  and 
the  lens  slightly  nearer  together  or  farther  apart  with- 
out visibly  impairing  the  definition  of  the  object  in 
question.  The  distance  through  which  the  ground 
glass  (or  the  lens)  may  be  moved  is  known  as  the  depth 
of  focus.  Obviously,  the  depth  of  field  and  depth  of 
focus  depend  on  the  manner  of  observing  the 
image,  since  if  a magnifying  lens  is  used  to  examine 
the  image  on  the  ground  glass  faulty  definition  be- 
comes more  apparent  than  it  would  be  to  the  un- 
aided eye,  the  circles  of  confusion  being  magnified. 
The  use  of  these  terms  therefore  implies  that  no  mag- 
nifer  is  used. 

Depth  of  field  and  depth  of  focus  are  functions  of 
the  focal  length  of  the  lens  and  of  the  size  of  the  stop 
used,  being  inversely  proportional  to  these  characteristics. 
That  is,  they  are  greater  in  a short  focus  lens  than  in 
one  of  greater  focal  length,  and  are  greater  with  a small 
stop  than  with  a large  one,  this  latter  fact  being  due  to 
the  circumstance  that  the  axial  rays  converge  at  a 
more  acute  angle  than  the  marginal.  Hence,  all  lenses 
of  the  same  focal  length  and  the  same  aperture  are 
identical  as  regards  depth  of  field  and  of  focus,  the 
frequent  claim  of  the  manufacturer  that  his  lenses  have 
great  depth  meaning  simply  that  they  are  so  well 
corrected  that  one  of  relatively  short  focal  length  may 
be  employed  with  a given  size  of  plate.  It  should  be 
noted  that  the  soft  focus  lens,  or,  in  fact,  any  un- 
corrected objective,  has  greater  apparent  depth,  both  of 
field  and  of  focus,  than  the  more  highly  corrected 
lens,  since  if  no  plane  is  sharply  defined  the  differ- 
ence in  definition  between  the  one  which  is  most 

42 


DIAPHRAGM  MARKINGS 


accurately  defined  and  those  which  are  out  of  focus 
is  less  apparent  than  when  one  is  microscopically 
sharp. 

In  fixed  focus  cameras  lenses  of  short  focal  length 
and  small  aperture  are  employed,  the  result  being  that 
the  depth  of  field  extends  from  a point  about  six  feet 
from  the  camera  to  infinity,  thus  obviating  the  necessity 
for  focussing.  Such  cameras  are  sometimes  called 
“universal  focus.” 

Diaphragm  Markings. — It  is  obvious  that  if  a 
small  aperture  is  used  less  light  will  reach  the  plate  in  a 
given  time  than  with  a large  one,  and,  since  the  sensi- 
tive emulsion  has  some  inertia,  that  is,  requires  some 
light  to  produce  any  chemical  action  whatever,  a longer 
exposure  will  be  necessary  if  a definite  effect  is  to  be 
obtained.  The  markings  of  the  apertures  furnish  an 
indication  of  the  relative  exposures  necessary  with  the 
various  stops,  and  there  are  two  systems  of  marking  in 
common  use,  the  F system  and  the  uniform  system 
(abbreviated  to  U.  S.).  In  the  former  the  number 
expresses  the  fraction  which  the  diameter  of  the  aper- 
ture is  of  the  focal  length  of  the  lens,  that  is,  F/8  means 

..  , , focal  length 

diameter  of  aperture  = — — , I /II  means 

focal  length 

diameter  of  aperture  = yy — — , etc.  bmce 

the  time  of  exposure  varies  inversely  as  the  area  of  the 
stop,  and  since  the  areas  of  circles  are  directly  propor- 
tional to  the  squares  of  their  diameters,  it  follows  that 
the  ratio  of  exposures  required  with  different  stops  is 

43 


THE  LENS 


the  ratio  of  the  squares  of  the  E numbers.  Thus,  F/16 
will  require  four  times  as  much  exposure  as  F/8,  since 

(10)2  = 256  and  (8)2  = 64,  and  - — - = 4.  Stops  are 

64 

usually  marked  in  such  a series  that  each  requires 
twice  as  much  exposure  as  the  next  larger,  the 
F series  being  F/4,  F/5.6,  F/8,  F/11.3  F/16,  F/22.6, 
F/32,  F/45,  F/64,  etc.  Intermediate  numbers,  such  as 
F/6.8,  F/7.7,  are  sometimes  used,  when  these  represent 
the  largest  aperture  of  the  lens.  In  the  uniform  system 
F/16  is  taken  as  the  arbitrary  unit,  and  is  called  U.  S. 
16,  the  other  apertures  being  so  marked  that  the  ratios 
of  the  exposures  are  directly  as  the  ratios  of  the  numbers, 
the  actual  diameters  of  the  openings,  in  inches,  remain- 
ing the  same  as  in  the  F system.  The  table  below  shows 
the  relation  between  the  two  systems,  and  the  exposures 


required : 

F System 

Uniform  System 

Relative  exposure  in 
seconds  or  minutes 

4 

1 

1 

5.6 

2 

2 

8 

4 

4 

11.3 

8 

8 

16 

16 

16 

22.6 

32 

32 

32 

64 

64 

45 

128 

128 

There  are  other  systems,  but  they  are  comparatively 
little  used. 

It  should  be  noted  that  when  one  combination  of  a 
symmetrical  lens  is  employed  the  stop  marldngs  no 
longer  represent  the  true  values  of  the  apertures.  Thus, 
suppose  the  case  of  a rapid  rectilinear  lens  of  eight 
44 


SPEEDS  OF  LENSES 


inches  focal  length,  working  at  a maximum  aperture  of 
F/8.  When  one  combination  only  is  used  the  focal 
length  becomes  sixteen  inches  (8X2).  Since  the  aper- 
ture of  the  whole  lens  is  F/8  and  the  focal  length  eight 
inches,  it  follows  that  the  aperture  has  a diameter  of 
one  inch,  and  the  working  aperture  of  the  single  com- 
bination becomes  F/16  (16/1  = 16).  Hence  the  single 
combination  will  require  four  times  the  exposure  of 
the  doublet. 

Speeds  of  Lenses. — Returning  now  to  the  matter 
of  lenses,  it  has  been  explained  that  a high  grade  lens 
is  one  which  has  been  so  well  corrected  for  optical 
errors  that  it  will  give  fine  definition  at  a large  aper- 
ture, but  that  the  same  result  may  be  attained  with  an 
uncorrected  lens  by  stopping  down,  and  the  following 
table  gives  a general  idea  of  the  largest  apertures  at 
which  different  types  of  lens  work,  though  it  must  be 
understood  that  these  figures  are  not  fixed,  but  vary 
with  different  manufacturers : 


Type  of  Lens"  Sharp  Definition  Pictorial  Work 

Spectacle  and  single  me- 
niscus  F/16 F/5.6  9 

Single  achromatic F/ll F/69 

Rapid  rectilinear F/8  (sometimes  F/ll,  more 

rarely  F/4) 

Anastigmat Varies  greatly.  Seldom 

smaller  than  F/6.8j^or 
larger  than  F/4 

Soft  focus F/16 F/6  for  single  lenses 

and  F/4  for  doublets 


9 The  apparent  anomaly  of  the  single  achromatic  working  at  a smaller 
aperture  than  the  less  fully  corrected  single  meniscus  is  explained  by  the 
fact  that  the  former  lens,  when  supplied  for  pictorial  work,  is  not  designed 
to  give  as  much  diffusion  as  the  latter. 


45 


THE  LENS 


Focal  Length  and  Perspective. — We  may  now 
take  up  the  question  of  the  proper  focal  length  of  the 
lens,  from  the  point  of  view  of  the  artist,  and,  as  stated 
in  Chapter  I,  it  will  almost  invariably  be  found  that 
when  a lens  is  furnished  with  the  camera  it  is  of  too 
short  a focal  length  to  be  desirable  for  pictorial  work. 
It  is  generally  said  that  a long  focus  lens  gives  better 
perspective  than  one  of  short  focal  length,  but  this  is 
not  quite  correct,  since  the  long  focus  lens  merely 
forces  the  camera  farther  from  the  object  in  order  to 
get  a given  size  of  image,  and  perspective  depends 
on  the  relative  distances  between  the  planes  of  the 


object  and  the  camera.  In  Figure  25  suppose  A and  B 

to  be  two  posts,  each  ten  feet  high,  the  distance  be- 

tween A and  B and  between  B and  the  camera  being 
one  hundred  feet.  Suppose  we  have  on  the  camera  a 
lens  of  ten  inches  focus,  then  a simple  proportion  gives 
the  sizes  of  the  images,  A'  and  B',  of  the  posts,  to  be 

10"  : 100'  : : B'  : 10'  hence  B'  = 1" 

10"  : 200'  : : A'  : 10'  hence  A'  = 3^" 

That  is,  the  image  of  A is  one-half  the  size  of  the  image 
of  B.  If,  now,  we  use  a twenty-inch  lens,  then  in  order 
that  the  image  of  B may  be  the  same  size  as  in  the 
first  case  it  will  be  necessary  to  set  the  camera  up  twice 
46 


FOCAL  LENGTH  AND  PERSPECTIVE 


as  far  from  B,  when  the  proportions  become  as  follows 
(Figure  26) : 

20"  : 200'  : : B'  : 10'  hence  B'  = l" 

20"  : 300'  : : A'  : 10'  hence  A' = 2/3" 

That  is,  the  image  of  A is  two-thirds  the  size  of  that  of 
B,  and  the  perspective  is  more  pleasing,  being  less 
abrupt,  though  it  should  be  noted  that  the  perspective 
in  the  first  case  is  absolutely  true,  being  what  an 
observer  would  see  if  he  stood  one  hundred  feet  from  B. 
If,  however,  the  ten-inch  lens  is  set  up  two  hundred 
feet  from  B the  ratio  of  the  two  images  will  be  the  same 


a b 


as  if  the  twenty-inch  lens  were  used,  each  image  being 
half  the  size  that  it  would  be  with  the  longer  focus 
objective,  and  if  the  smaller  negative  be  subsequently 
enlarged  two  diameters  the  final  result  will  be  the  same 
in  both  cases,  so  far  as  perspective  is  concerned.  It 
should  be  noted,  however,  that  the  use  of  a short  focus 
lens  and  subsequent  enlargement  results  in  greater 
depth  of  field  (and  of  focus)  since,  as  stated  above,  the 
depth  varies  inversely  as  the  focal  length  of  the  lens. 
Depth  of  focus  is  practically  always  desirable,  but 
depth  of  field  is  not  necessarily  so,  for  it  prevents  the 
worker  from  emphasizing  one  particular  plane  by  focus- 

47 


THE  LENS 


sing  on  it  more  sharply  than  on  the  others.  This 
greater  depth  of  field  is  one  of  the  chief  argu- 
ments brought  forward  by  the  advocates  of  the 
miniature  cameras,  but  each  worker  must  decide 
for  himself  whether  or  not  the  argument  is  valid  in 
his  own  case. 

If  the  lens  is  of  too  short  focal  length  it  will  be 
difficult  to  keep  far  enough  from  the  nearest  object  to 
insure  pleasing  perspective,  since  perspective  is  not 
very  apparent  on  the  ground  glass,  and  the  tendency  is 
to  approach  near  enough  to  get  the  principal  object 
of  the  desired  size.  On  the  other  hand,  if  the  lens  is 
of  too  great  a focal  length  it  will  often  be  found  difficult, 
by  reason  of  the  size  of  the  studio  or  the  configuration 
of  the  landscape,  to  get  far  enough  away  to  include  all 
that  is  wanted.  The  best  focal  length  of  lens  to  use 
for  general  purposes  with  any  given  size  of  plate  is 
found  by  adding  the  lengths  of  two  adjacent  sides  of 
the  plate.  Thus,  for  a 4X5  plate,  a 9"  lens  should  be 
employed,  for  6J^XB3^,  15",  for  8X10,  18",  etc.  This 
rule  is  purely  empirical,  but  gives  good  general  results, 
though  it  may  sometimes  be  advisable  to  modify  it 
somewhat.  For  example,  if  the  worker  is  using  a 4X5 
plate,  and  wishes  to  do  out-door  portraiture  or  to 
select  small  landscape  bits,  a 12"  lens  may  be  better, 
but  if  he  is  doing  studio  portraiture  or  wide  landscapes, 
one  of  8"  focal  length  may  be  preferable.  Generally, 
however,  a long  focal  length  is  to  be  preferred  to  a 
shorter  one. 

The  Pin-hole. — A device  which  is  sometimes  used 
in  pictorial  work,  and  which  presents  certain  advantages 
over  the  lens,  is  the  pin-hole,.  This  is  made  by  piercing 

48 


THE  PIN-HOLE 


a hole  from  1/50  to  1/20  inch  in  diameter  in  a thin 
plate,  which  is  usually  of  metal,  and  placing  this  plate 
in  the  front  of  the  camera,  to  project  an  image  on  the 
film.  As  stated  above,  every  point  of  a luminous  or 
reflecting  body  sends  out  rays  in  all  directions,  and  if 
the  pin-hole  were  of  sufficiently  small  dimensions  only 
one  ray  from  each  point  of  the  object  would  reach  the 
plate,  as  illustrated  in  Figure  27,  thus  forming  an  image 
of  the  point  on  the  sensitive  surface.  Since,  however, 
the  pin-hole  is  of  large  dimensions  as  compared  to  a 
ray  of  light  more  than  one  ray  from  each  point  will 


pass  through,  the  practical  result  being  a slight  blurring 
of  the  image,  which  blurring  may,  however,  be  reduced 
to  an  amount  inappreciable  to  the  eye  by  sufficiently 
reducing  the  diameter  of  the  hole.  It  should  be  noted, 
though,  that  if  the  diameter  of  the  hole  is  less  than 
1/75  inch  diffraction,  or  the  bending  of  light  rays  in 
passing  an  edge,  may  cause  the  image  to  be  somewhat 
lacking  in  definition,  so  it  is  not  possible  to  secure 
absolutely  sharp  images  by  reducing  the  size  of  the 
aperture.  Since  the  rays  are  not  refracted,  and  since 
there  are  no  reflecting  surfaces,  the  pin-hole  is  entirely 
free  from  optical  errors  and  from  flare,  and  for  the 


THE  LENS 


same  reason  (that  the  rays  travel  in  straight  lines 
throughout)  there  is  no  focal  point,  the  only  effect  of 
moving  the  plate  nearer  to  or  farther  from  the  pin-hole 
being  to  alter  the  size  of  the  image,  and,  of  course,  the 
amount  included  on  the  plate.  Hence  the  pin-hole  is 
equivalent  in  including  power  to  a battery  of  lenses  of 
all  focal  lengths.  As  a corollary,  the  pin-hole  may  in 
an  emergency  be  used  as  an  extreme  wide-angle  lens, 
having  been  successfully  used  with  so  short  a bellows 
extension  as  inches  on  an  8X10  plate,  the  angle  of 
view  in  that  case  being  142°.  Of  course,  since  the 
intensity  of  illumination  falls  off  with  the  distance 
which  the  pin-hole  (or  lens)  is  from  the  plate,  the  light 
being  spread  over  a greater  area,  a negative  made  in 
such  extreme  circumstances  will  show  less  exposure  at 
the  edges  than  at  the  center,  but  this  can  be  equalized 
in  printing. 

Since  light  is  propagated  in  straight  lines  outside 
as  well  as  inside  the  camera,  it  follows  that  the  pin- 
hole has  infinite  depth  of  field  as  well  as  of  focus,  all 
objects  within  the  field  of  view  being  equally  well 
defined.  This  may  be  an  advantage  or  the  reverse,  the 
former  because  stopping  down  a soft  focus  lens  to 
secure  depth  changes  the  quality  of  definition,  the  latter 
because  it  is  sometimes  desirable,  as  mentioned  above, 
to  emphasize  one  plane  by  focussing  on  it  more  sharply 
than  on  the  others. 

The  advantages  of  the  pin-hole,  then,  are  infinite 
depth  of  field  and  of  focus,  and  a very  pleasing  quality 
of  definition,  the  amount  of  diffusion  depending  on  the 
size  of  the  hole.  The  disadvantages  are  the  impossi- 
bility of  accenting  one  plane  at  the  expense  of  the  others, 

50 


THE  PIN-HOLE 


and  the  long  exposures  required.  More  or  less  com- 
plicated methods  of  calculating  the  exposure  required 
with  the  pin-hole  are  given  in  various  text-books,  but 
the  simplest  is  to  divide  the  diameter  of  the  hole  in 
inches  by  the  distance  which  it  is  from  the  plate,  and 
to  take  this  as  the  F number  of  the  hole  with  that  of 
bellows  extension.  (This,  obviously,  is  the  same  method 
that  is  employed  in  finding  the  F value  of  a lens  stop.) 
Thus  with  a hole  of  1 /20  inch  diameter  and  an  extension 
of  10  inches,  the  value  would  be  (1/20)  -5-10  = F/200.  In 
these  circumstances  the  exposure  for  a brightly  lighted 
landscape  at  mid-day  in  June,  using  a fast  plate,  would  be 
3 seconds,  whereas  with  a lens  working  at  F/8  it  would 
be  1/200  second.  It  will  thus  be  seen  that  the  use  of  a 
pin-hole  precludes  the  photography  of  moving  objects 
and  even  renders  it  impossible  to  do  landscape  work 
on  a windy  day,  while  it  is  entirely  out  of  the  question 
for  general  indoor  portraiture.  Within  these  limitations, 
however,  it  is  a very  useful  instrument. 

The  illumination  of  the  ground  glass  being  very 
feeble  when  a pin-hole  is  employed,  it  is  difficult  to 
locate  the  image  on  the  focussing  screen  with  the  hole 
to  be  used  for  exposure,  and  it  is  customary  to  sur- 
mount this  difficulty  by  the  use  of  an  auxiliary  hole  of 
about  1/8  inch  diameter,  which  gives  more  illumination 
and  at  the  same  time  affords  sufficient  definition  to 
permit  of  arranging  the  picture. 

In  describing  the  method  of  making  a pin-hole  the 
text-books  usually  give  elaborate  instructions  for  its 
manufacture,  these  directions  looking  toward  an  ac- 
curately gauged,  sharp-edged  hole.  The  writer  finds, 
however,  that  for  pictorial  work  it  is  sufficiently  ac- 

51 


THE  LENS 


curate  to  punch  a hole  with  a pin  or  needle  in  a piece 
of  black  paper  such  as  plates  are  wrapped  in,  as  the 
purpose  of  the  more  accurate  method  is  to  approximate 
lens  definition,  which  is  precisely  what  the  artist 
wishes  to  avoid. 

Discussion  of  the  Soft  Focus  Lens. — It  has  been 
said  that  the  primary  value  of  the  soft  focus  lens  de- 
pends on  the  fact  that  it  gives  a quality  of  definition 
approximating  that  of  the  eye,  but  there  are  two  other 
characteristics  which  go  to  make  this  type  of  objective 
desirable.  The  first  is  that  by  the  use  of  an  aperture 


Fig.  28. 


larger  than  normal  it  is  possible  to  obtain  greater  diffu- 
sion, thus  aiding  in  the  suggestion  of  mystery,  a sugges- 
tion which  is  of  importance  in  any  work  of  art,  and  the 
other  is  that  such  a lens,  properly  used,  gives  a vibrating 
quality  of  light  which  is  closely  akin  to  the  psychic 
suggestion  of  sunlight.  This  latter  characteristic  re- 
quires further  elucidation.  In  some  of  the  earlier  soft 
focus  lenses  diffusion  was  gained  by  means  of  spherical 
aberration,  and  if  Figure  28  be  examined  it  will  be  seen 
that  with  such  a lens  the  image  of  a point  of  light  will 
be  formed  partly  by  the  axial  and  partly  by  the  marginal 
52 


DISCUSSION  OF  SOFT  FOCUS  LENS 


rays,  and  partly  by  those  intermediate.  Hence  the 
image  of  such  a point  will  be  nearly  a uniform  disc  of 
light,  provided  the  plate  be  set  in  the  plane  of  least 
diffusion,  and  the  image  of  the  object  will  be  made  up 
of  a number  of  such  discs,  overlapping  one  another, 
thus  causing  diffusion.  Most  of  the  soft  focus  lenses 
now  on  the  market,  however,  gain  diffusion  by  means 
of  chromatic  aberration,  and  the  effect  is  indicated  in 
Figure  29.  Here  the  light  is  analyzed,  and  if  the  plate 
is  set  in  the  focal  plane  of  the  violet  rays,  which  have 


Fig.  29. 

the  most  intense  photographic  effect,  the  image  of  a 
luminous  point  will  be  a spot  of  intense  light  surrounded 
by  a halo  due  to  the  less  actinic  green  rays,  the  effect 
due  to  the  red  rays  being  practically  zero  unless  a pan- 
chromatic plate  is  used.  Hence  the  image  is  made  up 
of  an  infinite  number  of  intensely  illuminated  spots 
surrounded  by  less  intense,  but  moderately  sharp-edged 
halos,  and  the  effect  is  very  different  from  that  given 
by  spherical  aberration.  Since  the  violet  rays  are  the 
most  active  chemically  and  the  yellow  (green +red) 
are  the  most  luminous  to  the  eye,  it  follows  that  if  the 

53 


THE  LENS 


plate  be  set  at  the  visual  focus  the  point  will  be  due  to 
the  yellow  rays  and  will  be  faint,  whereas  the  halo, 
being  due  to  the  violet  rays  (which  will  be  out  of  focus), 
will  be  intense,  great  diffusion  resulting.  If,  on  the 
other  hand,  the  plate  be  set  at  the  focus  of  the  violet 
rays,  diffusion  will  be  least,  the  halo  being  caused  by 
the  green  rays.  A rough  empirical  rule  for  obtaining 
the  best  definition  at  a given  aperture  with  a soft  focus 
lens  is  to  focus  as  accurately  as  possible  on  the  principal 
object  and  then  move  the  ground  glass  nearer  to  the 
lens  until  the  principal  object  just  begins  to  be  out  of 
focus,  making  the  exposure  with  the  plate  in  this 
position. 

When  using  a lens  having  chromatic  aberration  a 
quality  of  definition  identical  with  that  seen  on  the 
ground  glass  may  be  secured  by  using  a fully  correcting 
ray-filter  and  focussing  and  exposing  with  it  in  posi- 
tion, since  the  ray -filter  absorbs  the  ultra-violet  and 
the  superfluous  violet  rays,  causing  the  residual  color 
sensitiveness  of  the  plate  to  coincide  wTith  that  of  the 
eye,  and,  of  course,  bringing  the  visual  and  the  chemical 
foci  into  the  same  plane.  The  use  of  a ray-filter  evi- 
dently presupposes  the  use  of  a color-sensitive  plate. 

It  is  often  stated  that  the  same  result  may  be 
secured  by  making  an  enlargement,  using  a soft  focus 
lens  for  projection,  as  would  be  obtained  if  the  original 
negative  were  made  with  a lens  of  this  type,  but  this 
is  not  quite  correct.  In  the  first  place,  if  a soft  focus 
lens  is  used  originally  the  plane  focussed  on  is  the 
sharpest,  diffusion  increasing  progressively  toward  the 
distance,  whereas  if  such  a lens  is  used  for  enlarging 
both  image  and  object  are  flat  planes,  so  that  diffusion 

54 


DISCUSSION  OF  SOFT  FOCUS  LENS 


is  uniform  throughout  the  enlargement,  regardless  of 
the  planes  in  which  the  various  portions  of  the  picture 
lie.  In  the  second  place,  the  halo  which  is  found  in  the 
image  given  by  a soft  focus  lens  consists  of  a breaking 
of  light  into  the  dark  spaces,  so  that  if  an  enlargement 
is  made  on  bromide  paper  from  a negative,  in  which  the 
lights  are  represented  by  dense  spaces  and  the  shadows 
by  more  translucent  ones,  the  finished  print  will  show 
a dark  halo  surrounding  the  shadows  and  extending 
into  the  lights,  the  effect  being  very  unpleasant,  and 
not  true  to  the  manner  in  which  the  eye  perceives 
objects.  If  an  enlarged  negative  be  made  with  a soft 
focus  lens  from  a transparency  this  effect  will  of  course 
be  as  it  should. 

Since  most  of  the  soft  focus  lenses  on  the  market  are 
of  the  single  type,  few  of  them  being  rectilinear,  it 
follows  that  they  cannot,  in  general,  be  used  for  archi- 
tectural work  as  such  with  entire  satisfaction.  It  has 
been  pointed  out,  however,  that  if  the  diaphragm  is 
between  the  lens  and  the  object  distortion  is  barrel 
shaped,  wdiereas  if  it  is  between  the  lens  and  the  image 
distortion  is  of  the  pin-cushion  type,  and  this  suggests 
a method  whereby  such  lenses  may  be  used  for  archi- 
tectural work  without  representing  straight  lines  as 
bowed.  If  an  enlargement  be  made  from  the  original 
negative,  using  the  same  lens  as  was  employed  for 
making  the  negative,  and  taking  care  to  place  the 
diaphragm  between  the  lens  and  the  enlargement,  the 
pin-cushion  distortion  in  the  enlargement  will  correct 
the  barrel-shaped  distortion  in  the  negative,  and  the 
final  result  will  be  rectilinear.  The  introduction  of 
additional  diffusion  in  enlarging  may  be  prevented  by 

55 


THE  LENS 


stopping  the  lens  down,  since  changing  the  size  of  the 
aperture  does  not  affect  distortion.  This  works  well  in 
practice,  the  results  being  all  that  could  be  desired. 

Generally  speaking,  the  soft  focus  lens  is  faster  at  a 
given  aperture  than  the  more  fully  corrected  one,  for, 
although  all  lenses  of  the  same  aperture  have  theo- 
retically the  same  speed,  an  anastigmat  or  rectilinear 
usually  has  a greater  thickness  of  glass  than  the  soft 
focus  objective,  and  the  absorption  of  light  in  the  glass 
may  operate  to  make  the  corrected  objective  much 
slower — 25  or  30  per  cent,  in  extreme  cases — than  the 
simpler  lens. 


THE  CAVE 

BY  CLARENCE  H.  WHITE 
From  a Platinum  Print 


CHAPTER  III 


PLATES— FILMS— RAY-FILTERS 

The  Spectrum. — It  has  already  been  explained  that 
white  light  consists  of  ether  vibrations  of  different  wave 
lengths,  the  visible  portion  of  the  spectrum  consisting 
of  wave  lengths  from  4000  to  7000  A.  U.  In  addition, 
there  are  known  to  exist  waves  of  much  less  and  much 
greater  wave  length,  the  former  being  known  as  ultra- 
violet and  the  latter  as  infra-red.  The  infra-red  rays 
manifest  themselves  as  heat  and  as  Hertzian  waves, 
and  are  of  no  great  importance  in  photography,  whereas 
the  ultra-violet  have  a marked  chemical  (photographic) 
action,  and  are  extremely  important.  If  a beam  of 
white  light  be  analyzed  by  means  of  a diffraction 
grating  it  will  appear  as  an  elongated  band  of  different 
colors,  as  shown  in  Figure  30,  where  the  numbers 
indicate  the  wave  lengths. 

Visual  Luminosity. — It  will  be  found  that  the 
visual  luminosity,  that  is,  the  intensity  to  the  eye,  of 
these  colors  varies,  the  yellow  being  the  most  intense, 
while  the  effect  falls  off  toward  both  ends  of  the  spec- 
trum, so  that  if  we  plot  a curve  in  which  vertical 
distances  represent  visual  luminosities  it  will  appear 
as  in  Figure  31. 

Ordinary  Plate. — Since  natural  objects  appear 
colored  by  reason  of  the  fact  that  they  absorb  all  light 
except  that  of  a certain  wave  length  (the  wave  length 
which  gives  rise  to  that  particular  color  sensation)  it 

57 


PLATES  — FILMS  — R A Y-FIL  TEES 


will  be  apparent  that  if  they  are  to  be  represented  by 
photography  in  their  correct  values,  that  is,  relative 
luminosities  in  monochrome,  the  sensitiveness  of  the 
plate  to  light  of  the  different  wave  lengths  should  be 
the  same  as  that  of  the  eye,  but  this  is  very  far  from 
being  the  case,  for  if  the  spectrum  be  photographed  on 
an  ordinary  (non-orthochromatic)  plate  and  the  result 
plotted,  the  curve  will  have  the  form  shown  in  Figure 


Ui.tRA-Vioi.eT  Buoe-ViOLET  C,Retri  Ten.  ow  Ret>  Iwra-R^p 


©000  4000  5000  6000  7000 

Fig.  30. 

Ui.tra-Vioi.ET  Bv.ue-\AoutT  GREEN  Veu_ow  Reo  Infra- Reo 

3000  4000  5000  6000  7000 


Fig.  31. 


32.  That  is,  the  plate  is  sensitive  to  the  ultra-violet, 
which  is  entirely  invisible  to  the  eye,  has  its  maximum 
sensitiveness  in  the  violet,  to  which  the  eye  is  compara- 
tively insensitive,  is  only  slightly  sensitive  to  the  green, 
and  is  totally  insensitive  to  yellow  and  red.1 

1 A yellow  or  red  object  may,  it  is  true,  be  photographed,  by  reason 
of  the  fact  that  a small  percentage  of  white  light  is  reflected  unchanged  from 
the  surface  of  the  object,  but,  though  red  or  yellow  is  not  rendered  as  abso- 
lutely black,  as  would  be  the  case  if  a pure  spectrum  were  photographed,  it 
will  still  be  reproduced  as  much  too  dark. 

58 


THE  SPECTRUM 


Orthochromatic  Plate . — It  is  possible,  by  adding 
certain  dyes  to  the  emulsion,  either  at  the  time  of 
manufacture  or  by  bathing  the  plate  afterward,  to 
extend  the  sensitiveness  somewhat,  producing  what  is 
known  as  an  orthochromatic  (“right-colored”)  or  iso- 
chromatic  (“equally-colored”)  plate,  and  the  color- 
sensitiveness curve  of  such  a plate  is  shown  in  Figure  33. 
It  will  be  seen  that  this  plate  is  sensitive  to  green  and 


Ultra-Violet  Blue-Violet  ^reew  Tellov*  Rep  \hfra-Rep 


Ultra-Violet  Blue-Violet  CjReem  \ellow  Rep  Iaera-Reo 


Fig.  33. 


yellow  in  addition  to  the  ultra-violet,  violet,  and  blue- 
green,  but  still  remains  insensitive  to  red,  and  is  but 
slightly  sensitive  to  yellow,  while  retaining  the  ultra- 
violet sensitiveness. 

Panchromatic  Plate. — Certain  other  dyes,  if  added 
to  the  emulsion,  render  it  sensitive  to  all  visible  light, 
and  such  plates  are  called  panchromatic  (“all-colored”) 
trichromatic  (“three-colored”)  or  spectrum  plates,  the 
color-sensitiveness  curve  of  such  emulsions  being  shown 

59 


PLATES  — FILMS  — E A Y-EILTERS 


in  Figure  34.  It  will  be  seen  from  the  preceding  dia- 
grams that  all  plates,  whether  ordinary,  orthochromatic, 
or  panchromatic,  are  excessively  sensitive  to  violet, 
which  is  dark  to  the  eye,  and  to  ultra-violet,  which  is 
totally  invisible,  and  in  order  to  correct  this  faulty 
sensitiveness  it  is  necessary  to  employ  a device  known 
as  a ray-filter  or  ray-screen,  but  before  discussing  the 
filter  we  will  first  consider  the  effect  of  photographing 
without  it. 

Anti-Screen  Plate— There  is  another  type  of  ortho- 
chromatic  plate,  known  as  the  “anti-screen”  or  “non- 


Ultra-Violet  Blue-Violet  <tRSeis  Yello*  Re-P  Imfra-ReV 


filter,”  in  which  additional  dyes  beyond  those  required 
for  orthochromatizing  have  been  added  to  the  emulsion, 
and  this  plate  is  widely  advertised  as  giving  correct 
values  without  a filter,  but,  as  will  be  seen  later,  such 
claims  are  without  practical  foundation,  this  plate  offer- 
ing no  advantages  over  the  orthochromatic  so  far  as 
actual  work  is  concerned,  whatever  improvement  of 
color  rendering  may  be  shown  in  the  laboratory,  so  it 
will  not  be  considered  separately. 

Color- Sensitiveness  Percentages . — In  “ Orthochro- 
matic Filters”  Dr.  C.  E.  K.  Mees  gives  the  following 
table  of  the  sensitiveness  percentages  of  different  types 
of  plate: 

60 


FIG.  35.— COPIES  OF  COLOR  CHART  WITH  VARIOUS  PLATE  AND  FILTER  COMBINATIONS 


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TEST  CHART 


Type  of  Emulsion  Ultra-Violet  and  Violet  Color  Sensitiveness 

Sensitiveness  (Green,  Yellow  and  Red) 

Orthochromatic 95  to  98  per  cent.  2 to  5 per  cent. 

Anti-Screen 90  to  94  per  cent.  6 to  10  per  cent. 

Panchromatic 82  per  cent.  18  per  cent. 

To  these  we  may  add 

Ordinary 100  per  cent.  0 per  cent. 


for,  although  yellow  and  red  will  register  on  an  ordinary 
plate  if  sufficient  exposure  be  given,  so  long  a time  will 
be  required  that  the  other  colors  will  be  tremendously 
over-exposed. 

Test  Chart. — One  of  the  problems  set  by  the 
writer  for  his  students  is  the  photographing  of  a test 
chart,  so  as  to  show  practically  the  rendering  of  colors 
by  different  combinations  of  plates  and  filters,  and  a 
reproduction  of  the  result  is  given  in  Figure  35,  the 
photographs  having  been  made  by  Mr.  W.  R.  Latimer, 
class  of  1915.  The  chart  consists  of  a scale  of  five  grays, 
with  the  colors  violet,  blue,  blue-green,  green,  yellow- 
green,  yellow,  orange,  and  red,  and  it  was  photographed 
on  an  ordinary  plate;  on  an  orthochromatic,  with  and 
without  a filter;  on  an  anti-screen,  with  and  without  a 
filter;  and  on  a panchromatic,  with  and  without  a filter, 
exposure  and  development  being  adjusted  so  that  the 
scale  of  grays  was  rendered  alike  in  all  the  prints.  The 
panchromatic  plate  with  the  filter  gave  a correct  ren- 
dering of  the  relative  brightness  of  the  different  colors, 
and  an  examination  of  the  figure  will  show  to  what 
extent  the  rendering  of  the  other  plates  is  faulty.  It 
should  be  borne  in  mind  that  this  test  is  more  favor- 
able to  the  ordinary,  orthochromatic,  and  anti-screen 
plates  than  would  be  the  case  if  it  had  been  made  with 
a spectroscope,  since  all  the  colors  of  the  chart  reflect 

61 


PLATES  — FILMS  — RAY-FILTERS 


some  white  light,  and  the  conditions  are  therefore  more 
nearly  those  of  actual  practice. 

Photographing  Without  a Ray-Filter. — When 
white  light,  that  is,  light  containing  all  wave  lengths, 
such  as  ordinary  sunlight,  falls  on  any  natural  object 
a portion  is  reflected  unchanged  from  the  surface,  part 
is  absorbed  and  quenched,  and  the  remainder  pene- 
trates a short  distance  below  the  surface  and  is  then 
reflected,  the  last  portion  being  that  which  gives  the 
object  its  color.  It  will  be  apparent  that  when  this  part 
is  of  a wave  length  to  which  the  plate  is  insensitive  the 
object  is  photographed  entirely  by  that  portion  of  the 
superficially  reflected  white  light  to  which  the  plate  is 
sensitive,  and,  the  violet  sensitiveness  of  the  plate  being 
so  far  in  excess  of  the  color  sensitiveness,  this  is  what 
practically  always  occurs  unless  a filter  is  used.2  The 
practical  results  of  this  fact  will  be  considered  so  far  as 
landscape  and  portraiture  are  concerned,  since  if  the 
fundamental  principles  are  grasped  they  may  be  applied 
to  architecture,  genre,  and  other  forms  of  work  by 
anyone. 

In  landscape,  assuming  a sunny  day,  we  find  the 
sky  to  be  a very  intense  blue,  sunlit  foliage  a yellow- 
green,  and  foliage  in  shadow  to  be  a blue-green,  the 
last-named  being  illuminated  entirely  by  reflected  light 
from  the  sky.  Hence  we  may  expect  the  sky  to  photo- 
graph as  very  much  lighter  than  it  should,  and,  in  fact, 
its  actinic  value  is  so  nearly  that  of  white  that  light 
clouds  will  be  entirely  lost,  so  far  as  printing  value  is 

2 Early  in  the  morning  and  late  in  the  afternoon  the  sun’s  rays  pass 
through  a stratum  of  relatively  dense  air  carrying  a higher  percentage  of 
moisture  than  that  through  which  they  pass  near  the  middle  of  the  day, 
and  this  air  may  act  to  some  extent  as  a ray-filter. 

62 


WITHOUT  A RAY-FILTER 


concerned,  though  they  may  sometimes  be  distin- 
guished in  the  negative.  Foliage  in  shadow  will  photo- 
graph about  as  it  should,  the  blue  component  of  its 
illumination  balancing  to  a great  extent  its  local  color, 
but  foliage  in  sunlight  will  be  darker  than  should  be 
the  case.  Hence  the  foreground  will  be  flat  and  lacking 
in  contrast,  the  sky  will  be  far  too  light,  and  clouds 
will  not  be  retained  unless  they  are  very  heavy,  even 
heavy  clouds  being  incorrectly  rendered.  In  addition, 
ultra-violet  light  is  markedly  scattered  by  traces  of 
moisture  in  the  air,  so  that  the  middle  distance  and  the 
distance  will  be  too  light  in  value.  If,  however,  a suit- 
able ray-filter  is  used  and  exposure  and  development 
are  approximately  correct,  the  values  throughout  will 
be  rendered  exactly  as  they  appear  to  the  eye,  and  it 
may  be  noted  that  since  there  is  seldom  any  great 
amount  of  red  in  a landscape  an  orthochromatic  plate 
is,  generally  speaking,  as  good  as  a panchromatic  for 
this  purpose,  though  if  the  ray-filter  is  to  be  omitted 
a panchromatic  plate  should  be  used,  on  account  of  its 
greater  color  sensitiveness. 

In  portraiture,  however,  the  case  is  somewhat  dif- 
ferent, and  here  the  panchromatic  plate  is  invariably 
superior  to  any  other,  for,  though  falsification  of  values 
is  sometimes  desirable  in  landscape,  for  pictorial  reasons, 
correct  rendering  is  always  desirable  in  portraiture. 
It  is  of  course  obvious  that  when  it  is  said  that  the 
panchromatic  plate  is  invariably  superior  to  any  other 
it  is  assumed  that  the  photograph  is  to  be  made  by 
white  light  or  by  some  illumination  containing  a suit- 
able proportion  of  yellow  and  red,  for,  naturally,  if  the 
mercury  vapor  arc  is  employed,  a color  sensitive  plate 

63 


PLATES  — FILMS  — RAY-FILTERS 


presents  no  advantages  over  an  ordinary,  the  light  in 
question  containing  no  rays  except  ultra-violet  and 
violet.  However,  it  is  assumed  that  the  reader  knows 
better  than  to  expect  a correct  rendering  of  colored 
objects  by  monochromatic  light,  since  it  makes  no 
difference  whether  the  plate  is  color  blind  or  the  object 
reflects  no  colored  light.  The  skin  of  a healthy  Cau- 
casian is  distinctly  yellow,  with  an  element  of  red  in 
lips  and  cheeks,  hair  usually  tends  to  warm  brown, 
though  in  some  individuals  it  may  be  yellow  or  red, 
eyes  are  usually  of  a bluish-gray,  though  sometimes 
brown,  and  skin  blemishes  are  yellow  or  reddish. 
Wrinkles  have  a reddish  tendency,  due  to  small  capil- 
laries lying  near  the  surface,  and  the  faint  lines  under 
the  eyes  are  purplish  in  hue.  Hence  we  may  expect 
an  ordinary  or  orthochromatic  plate  to  render  the  skin, 
hair,  lips,  skin  blemishes,  wrinkles,  and  lines  under  the 
eyes  as  too  dark,  and  the  eyes  themselves  as  either  too 
light  or  too  dark.  In  addition,  since  the  shadows  of 
the  face  are  usually  of  a different  color  than  the  lights, 
being  illuminated  by  reflected  light,  it  follows  that  the 
planes  will  be  falsified,  and  this  faulty  rendering  of 
planes  may  completely  change  the  expression  of  the 
face.  A comparison  of  the  rendering  of  the  ordinary 
and  the  panchromatic  plates  is  given  in  Figure  36, 
which  was  made  in  an  ordinary  studio,  A having  been 
made  on  an  ordinary  plate,  and  B on  a panchromatic 
plate  with  a ray -filter.  No  retouching  or  modifying  of 
any  sort  has  been  done  on  either  of  these  negatives  or 
prints,  and  attention  should  be  called  to  the  fact  that 
B is  an  exact  rendering  of  the  sitter’s  appearance.  No 
ordinary  or  even  orthochromatic  plate  can  render 
64 


FIG.  36A— TAKEN  ON  ORDINARY  PLATE  FIG.  36B.— TAKEN  ON  PANCHROMATIC  PLATE  WITH 

FULLY  CORRECTING  FILTER 


THE  RAY-FILTER 


correctly  a subject  containing  so  much  yellow  and  red 
as  the  face,  even  with  a ray-filter,  and  if  true  values 
are  to  be  obtained  in  portraiture  a panchromatic  plate 
and  filter  are  absolutely  necessary.  It  is  proof  of  the 
remarkable  complaisance  and  equally  remarkable  lack 
of  observation  on  the  part  of  the  public  that  portraits 
made  on  non-color-sensitive  plates  have  been  and  still 
are  being  accepted  by  the  sitters.  In  fact,  it  is  doubtful 
if  one-tenth  of  one  per  cent,  of  the  professional  portrait 
photographers  in  this  country  at  the  present  time  use 
panchromatic  plates  in  regular  studio  work,  whereas  it 
may  safely  be  said  that  if  they  realized  the  advan- 
tages of  such  emulsions  all  except  the  very  lowest 
class  would  at  once  discard  the  ordinary  and  even  the 
orthochromatic  plate. 

The  Ray-Filter. — From  what  has  been  said  it  is 
apparent  that  in  photographing  on  an  ordinary,  ortho- 
chromatic  or  anti-screen  plate  we  are  photographing 
practically  entirely  by  ultra-violet  and  violet  light,  and 
even  if  a panchromatic  plate  be  used  this  is  to  all 
intents  and  purposes  the  case,  so  that  it  is  only  in 
exceptional  circumstances  that  the  values  can  be  ren- 
dered as  they  appear  to  the  eye.  If,  however,  some 
means  be  employed  to  subdue  the  excessive  effect  of 
the  ultra-violet  and  violet  rays,  as  well  as  a portion  of 
the  green,  thus  allowing  the  yellow  and  red  oppor- 
tunity to  act  on  the  emulsion  before  the  effect  of  the 
other  rays  has  become  excessive,  we  can  obtain  correct 
values.  Such  a means  is  the  ray-filter,  which  consists 
of  a sheet  of  suitably  dyed  gelatine  cemented  between 
two  pieces  of  glass  and  arranged  so  that  it  may  be 
interposed  between  the  plate  and  the  object  photo- 

5 65 


PLATES  — FILMS  — It  A Y-FILTERS 


graphed,  usually  either  immediately  in  front  of  the 
lens  or  immediately  behind  it.  Filters  are  of  two  sorts, 
corrective  and  selective,  the  former  having  its  absorp- 
tion of  light  so  adjusted  that  the  sensitiveness  curve 
of  the  plate  when  used  with  the  filter  corresponds  to 
that  of  the  eye  (except,  of  course,  that  the  ortho- 
chromatic  plate  has  no  red  sensitiveness),  whereas 
selective  filters  are  so  adjusted  as  to  pass  only  a certain 
portion  of  the  rays,  thus  emphasizing  one  region  of  the 
spectrum  at  the  expense  of  the  remainder.  For  instance, 
a red  filter  such  as  is  used  in  three-color  work  transmits 
only  red  rays,  absorbing  the  ultra-violet,  violet,  green, 
and  part  (the  green  component)  of  the  yellow.  Hence, 
if  objects  be  photographed  through  such  a filter  any 
red  portions  will  appear  bright,  since  the  light  from 
these  acts  on  the  plate,  all  other  colors  seeming  exces- 
sively dark.  Selective  filters  are  of  value,  generally 
speaking,  only  to  process,  commercial,  and  scientific 
workers,  so  will  not  be  discussed  here,  readers  who  are 
interested  being  referred  to  the  books  by  Dr.  Mees,  of 
the  Eastman  Kodak  Company,  and  to  the  publications 
of  the  G.  Cramer  Dry  Plate  Company. 

There  are  many  different  makes  of  filter  on  the 
market,  some  of  them  valuable  and  others  worse  than 
useless,  for  it  is  quite  possible  to  over-correct  a filter, 
that  is,  to  give  it  an  excessive  absorption  in  one  region 
of  the  spectrum,  say  the  violet  and  green,  so  that 
yellow  and  red,  when  photographed  through  the  filter, 
will  appear  too  light  as  compared  to  the  other  colors. 
Furthermore,  since  not  all  makes  of  plate  of  one  type 
have  the  same  color-sensitiveness  (not  being  sensitized 
with  the  same  dyes)  and  since  a panchromatic  plate 

66 


THE  RAY-FILTER 


may  require  an  entirely  different  absorption  from  an 
orthochromatic,  it  is  strongly  recommended  that  the 
worker  either  obtain  his  ray-filter  from  the  manu- 
facturers of  the  plate  with  which  it  is  to  be  used  or 
else  make  careful  tests  on  a color  chart.  Attention 
should  be  drawn  to  the  fact  that  even  the  use  of  a pan- 
chromatic plate  and  an  adjusted  filter  will  not  neces- 
sarily insure  correct  color  rendering,  since  incorrect 
exposure  will  result  in  rendering  some  colors  as  too 
dark  or  too  light,  though  there  is  considerable  latitude 
in  this  respect,  owing  to  the  accommodation  of  the  eye. 

Some  persons  object  to  the  use  of  a ray -filter  on  the 
ground  that  it  prolongs  exposure  unduly,  but  this  is 
not  the  case.  Of  course,  it  necessitates  somewhat  longer 
exposures,  since  some  of  the  light  which  would  other- 
wise act  on  the  plate  is  absorbed  by  the  filter,  but 
filters  may  be  obtained  which  give  partial  correction, 
with  a decided  improvement  in  color  rendering,  and 
require  only  twice  the  exposure  necessary  for  the  un- 
screened plate,  while  filters  are  to  be  had  which  give 
full  correction  and  call  for  a multiplying  factor  of  only 
five,  this  being  a great  improvement  on  the  old  ones, 
with  some  of  which  the  factor  was  as  high  as  eighteen, 
that  is,  the  exposure  with  the  filter  was  eighteen  times 
that  without.  It  may  be  said  that  if  a filter  requires 
more  than  five  times  the  exposure  which  would  be 
necessary  without  it,  that  filter  is  either  over-corrected 
or  is  inefficient,  though  this  must  be  understood  as 
applying  only  to  corrective  filters;  selective  filters  often 
necessarily  require  more  increase  of  exposure  than  this, 
as  will  be  realized  after  brief  reflection.  That  a factor 
of  five  does  not  necessitate  unduly  long  exposures  may 

67 


PLATES  — FILMS  — RAY-FILTERS 

be  judged  from  the  fact  that  the  writer  has  made  fully 
exposed  negatives  in  a moderately  well-lighted  room 
at  11.00  A.  M.  in  May  with  an  exposure  of  1/5  second, 
using  a lens  working  at  F/5.6  and  a fast  panchromatic 
plate.  Had  the  filter  been  used  this  would  have  meant 
an  exposure  of  one  second,  which  is  quite  within  reason 
for  practically  all  purposes.  So  far  as  landscape  is 
concerned,  the  writer  has  never  had  to  discard  the 
filter  on  account  of  time  of  exposure  except  when  work- 
ing by  moonlight.  Practically  all  the  writer’s  nega- 
tives are  made  with  a fully  correcting  filter,  the  screen 
being  discarded  only  when  falsification  of  values  is 
desired,  such  as  exaggeration  of  atmospheric  perspec- 
tive, or  when  photographing  children  indoors  with  poor 
light  conditions.  The  matter  of  exaggeration  of 
atmospheric  perspective  may  require  some  further 
elucidation,  and  it  will  be  remembered  that  mention 
has  been  made  of  the  fact  that  ultra-violet  light  is 
strongly  scattered  by  traces  of  moisture  in  the  air.  It 
is  well  known  that  on  a misty  day  the  distance  ap- 
pears much  higher  in  value  than  when  the  air  is  clear, 
this  being  due  to  the  fact  that  the  particles  of  water 
vapor  reflect  light  back  to  the  eye,  without  permitting 
it  to  reach  the  objects  included  in  the  landscape,  thus 
giving  the  appearance  of  a veil  drawn  over  the  distance. 
This  effect  is  observable  in  a lesser  degree  at  all  times, 
and  furnishes  one  of  the  means  whereby  we  estimate 
distance,  whence  the  term  atmospheric  perspective. 
Ultra-violet  light  is  scattered  more  strongly  by  mist 
than  the  rays  included  in  the  visible  portion  of  the 
spectrum,  and,  since  ultra-violet  light  affects  the  plate 
more  strongly  than  the  rays  of  a greater  wave  length, 
68 


THE  RAY-FILTER 


it  follows  that  when  any  moisture  is  present  in  the  air 
the  distance  will  appear  lighter  to  the  plate  than  to  the 
eye.  If  a suitable  ray -filter  is  used,  however,  the  effect 
on  the  plate  will  be  identical  with  the  visual  effect. 
Still,  judgment  must  be  used,  as  a single  instance  from 
the  writer’s  experience  will  show.  A photograph  was 
made  of  a winding  path  in  a park,  a figure  being  posed 
in  the  middle  distance,  and  practically  no  sky  being 
included  in  the  view.  The  path  was  of  a bluish-gray 
gravel,  and  was  bordered  by  green  lawns,  the  light 
values  of  gravel  and  grass  being  nearly  the  same, 
though,  by  reason  of  the  difference  in  color,  the  path 
was  clearly  visible  to  the  eye.  Had  a filter  been  em- 
ployed, it  would  have  been  almost  impossible  to 
distinguish  the  path  from  the  lawn  in  the  negative, 
but  the  filter  was  omitted,  and  the  path  photographed 
much  lighter  than  the  grass.  The  values  in  the  print 
were  of  course  untrue  to  nature,  but  the  pictorial  result 
was  good. 

The  writer  strongly  recommends  that  the  worker 
select  one  plate  and  adhere  to  it  throughout,  and 
advises  a fast  panchromatic  plate,  since  this  will  do  all 
that  any  other  will,  and  a great  deal  that  no  other  will 
accomplish,  this  advice  being,  of  course,  based  on  the 
supposition  that  the  photographer  intends  to  do  various 
kinds  of  work.  As  explained  above,  if  landscape  work 
only  is  to  be  done,  an  orthochromatic  emulsion  is 
practically  as  good  as  the  panchromatic.  It  is  true  that 
a panchromatic  plate,  being  sensitive  to  all  visible 
light,  cannot  conveniently  be  developed  by  inspection, 
but  this  fact  involves  no  hardship  to  one  who  employs 
tank  development,  which  is  recommended  in  any  case. 

69 


PLATES  — FILMS  — R A Y-FILTERS 


Those  workers  who  regard  development  as  a form  of 
recreation  will  object  to  the  use  of  the  tank,  and  as  a 
consequence  debar  themselves  from  enjoying  the  ad- 
vantages of  panchromatic  plates,  but  those  who,  like 
the  writer,  consider  the  negative  merely  as  a means  to 
an  end,  are  free  to  use  fully  color-sensitive  emulsions, 
and  will  find  that  they  present  many  advantages  over 
others,  not  least  among  them  being  the  elimination  of 
retouching,  since  freckles  and  wrinkles  are  not  exag- 
gerated, and  the  values — and  consequently  the  planes — 
are  rendered  precisely  as  they  appear  to  the  eye. 

Halation. — It  will  in  practically  all  cases  be 
found  advantageous  to  use  a plate  which  is  halation- 
proof,  such  a one  being  almost  imperative  in  landscape 
work,  so  we  will  next  consider  the  question  of  halation 
and  the  various  methods  of  preventing  it.  It  has 
already  been  stated  that  when  a ray  of  light  passes 
from  one  medium  to  another  of  different  refractive 
index  there  is  some  reflection  from  the  surface  where 
the  two  mediums  join,  and  it  is  this  fact  which  is  re- 
sponsible for  halation,  as  will  be  understood  on  referring 
to  Figure  37,  which  represents  a sectional  view  of  a dry 
plate  with  a ray  of  light  incident  on  it  from  the  lens. 
If  the  light  is  allowed  to  act  for  a sufficiently  long  time 
the  inertia  of  the  emulsion  is  completely  overcome  and 
the  light  passes  through  it  to  the  glass,  part  of  it  being 
reflected  back  in  the  manner  shown,  to  a path  some 
distance  from  its  original  path  through  the  film,  where 
it  produces  a secondary  effect  on  the  emulsion.  This 
manifestation  is  apparent  whenever  a plate  not  espec- 
ially prepared  is  used  to  photograph  a subject  having 
strong  contrasts,  such  as  a landscape  with  sky,  an 

70 


HALATION 


interior  with  windows,  or  a white  dress  against  a dark 
background,  and  it  shows  itself  in  the  form  of  a halo 
spreading  from  the  light  spaces  into  the  dark  ones.  It 
may  be  avoided  to  some  extent  by  special  methods  of 
development  or  be  corrected  by  after-treatment  of  the 
negative,  but  the  simplest  means  is  to  use  a non-halation 


Fh_n\  C^uass 


plate.  There  are  several  ways  of  preparing  such  plates. 
(1)  Double-coating,  that  is,  placing  a slow  emulsion 
on  the  glass  and  a fast  one  on  that,  so  that  the  shadows 
will  be  recorded  on  the  fast  emulsion  before  the  lights 
have  had  time  to  overcome  the  inertia  of  the  slow  one. 
This  method  is  the  usual  one  in  America,  the  Standard 
Orthonon,  the  Seed  and  Hammer  Non-Halation,  and 

71 


PLATES  — FILMS  — RAY-FILTERS 


the  Cramer  Double-Coated  being  typical  plates  of  this 
class.  (2)  Using  the  same  emulsion  throughout  but 
making  it  very  thick,  so  that  it  has  great  inertia  to  the 
lights  but  little  to  the  shadows.  The  writer  knows  of 
but  two  manufacturers  who  employ  this  method,  the 
G.  Cramer  Dry  Plate  Company,  whose  Portrait  Isonon 
and  Commercial  Isonon  plates  are  of  this  class,  and  the 
Central  Dry  Plate  Company.  Methods  (1)  and  (2) 
possess  the  advantage  of  giving  plates  with  great 
latitude,  that  is,  if  the  subject  be  a normal  one  the 
exposure  may  be  many  times  normal  without  causing 
the  negative  to  show  signs  of  over-exposure.  (3) 
Backing.  That  is,  placing  an  opaque  or  non-actinic 
film  of  about  the  same  refractive  index  as  glass  in 
optical  contact  with  the  back  of  the  plate,  so  that 
any  light  which  reaches  the  back  of  the  glass  is  absorbed 
by  the  backing.  This  method  is  the  one  most  common 
in  England,  the  Wratten  Panchromatic  plate  being  of 
this  type.  Backing  is  as  efficient  in  preventing  halation 
as  double  coating,  but  the  latitude  is  of  course  no 
greater  than  that  of  an  unbacked  plate.  (4)  Coating 
the  emulsion  on  a thin  support,  such  as  a celluloid  film 
or  a sheet  of  paper.  In  this  case  the  reflected  light 
returns  into  the  emulsion  so  near  its  original  path  that 
halation  is  not  apparent.  (5)  Placing  between  the 
glass  and  the  emulsion  a film  of  some  non-actinic  dye, 
which  is  discharged  either  in  developing  or  in  fixing. 
Some  French  and  German  manufacturers  use  this 
method,  but  it  is  not  customary  in  either  America  or 
England,  though  quite  as  efficient  as  any  other  means. 
(6)  Incorporating  hydrazine  with  the  emulsion.  There 
is  on  the  market  a non-halation  plate  made  in  this  fash- 
72 


HALATION 


ion,  and  it  is  extremely  efficient.  (7)  In  addition  to 
the  above,  it  may  be  observed  that  halation  can  often 
be  diminished  or  prevented  by  exposing  with  the  glass 
side  toward  the  lens,  etc.  If  this  method  is  adopted 
it  is  advisable  to  clean  the  glass  side  of  the  plate  thor- 
oughly before  placing  it  in  the  holder. 

In  connection  with  backing,  two  points  should  be 
noted.  First,  that  the  backing  must  have  approxi- 
mately the  same  refractive  index  as  glass  and  must  be 
in  optical  contact  with  it,  so  that  the  plan  of  lining  the 
plate-holders  with  black  paper  or  cloth,  as  advised  by 
some  writers,  is  of  no  value,  and,  second,  that  a red 
backing,  though  useful  with  ordinary  or  orthochromatic 
plates,  is  not  recommended  for  use  with  panchromatic 
emulsions,  in  which  case  the  backing  should  be  black. 
If  the  worker  wishes  to  back  his  own  plates  he  may  do 
so  by  clamping  them  in  a printing-frame,  glass  side  out, 
and  brushing  with 


Mucilage 1 ounce 

Caramel 1 ounce 

Burnt  Sienna,  ground  in  water 2 ounces 

Mix  and  add 

Alcohol 2 ounces 


This  formula  is  taken  from  the  British  Journal  Alma- 
nac, and  is  obviously  intended  for  ordinary  or  orthochro- 
matic plates,  but  there  seems  to  be  no  reason  why 
lampblack  or  ivory  black  should  not  be  substituted 
for  the  burnt  sienna,  thus  rendering  it  suitable  for 
panchromatic  plates.  After  brushing,  the  plates  should 
be  allowed  to  dry  in  the  dark.  If  preferred,  the  plates 
may  be  clamped  film  to  film  in  pairs,  and  dipped  into 
the  backing  mixture. 


73 


PLATES  — FILMS  — RAY-FILTERS 


Bromide  Paper. — It  is  quite  possible  to  use  bromide 
paper  instead  of  plates  for  making  negatives  direct  in 
the  camera,  the  advantages  being  lightness,  freedom 
from  danger  of  breakage,  compactness  in  storing, 
freedom  from  halation,  ease  of  modifying  the  negatives 
with  pencil  or  stump,  and  the  fact  that  the  grain  of  the 
paper  imparts  an  interesting  texture  to  the  print.  The 
disadvantages  are  that  bromide  paper  is  obtainable 
only  in  ordinary  emulsions,  that  it  requires  slightly 
longer  to  print,  and  that  the  speed  is  from  1/20  to  1/100 
that  of  the  average  plate.  It  is  apparent  that  the 
worker  who  desires  to  use  this  method  should  choose 
a fast  emulsion,  coated  on  a thin,  smooth  stock,  and  it 
is  further  to  be  observed  that  if  the  negatives  are 
smaller  than  6^X8^  the  grain  of  the  paper  is  likely 
to  become  unpleasantly  apparent.  Nevertheless,  within 
these  limitations  paper  negatives  are  capable  of  giving 
good  results,  as  is  shown  by  the  fact  that  all  of  D.  O. 
Hill’s  magnificent  portraits  were  printed  from  such 
negatives,  and  by  the  fact  that  many  of  the  best 
workers  use  bromide  paper  exclusively  for  enlarged 
negatives,  this  fact  being  considered  further  in  Chap- 
ter VII. 

Plates  or  Films. — Much  discussion  has  been  in- 
dulged in  as  to  the  relative  advantages  of  coating  the 
sensitive  emulsion  on  glass  plates  or  on  celluloid  films, 
and  it  is  almost  impossible  to  convince  the  adherents 
of  either  method  that  there  is  any  value  in  the  other. 
It  may  be  stated  that  the  writer  is,  generally  speaking, 
an  advocate  of  the  plate,  but  the  advantages  and 
disadvantages  of  plates  and  films  will  be  considered 
impartially. 

74 


PLATES  OR  FILMS 


The  advantages  of  dry  plates  as  compared  to  roll 
films  or  film  packs  are  as  follows. 

(1)  They  may  be  obtained  in  ordinary,  ortho- 
chromatic,  or  panchromatic  emulsions,  and  of  practic- 
ally any  desired  speed.  Films  are  practically  all  of  the 
fast  orthochromatic  type. 

(2)  They  may  be  obtained  double-coated.  Films 
are  all  single-coated. 

(3)  For  some  unknown  reason,  an  emulsion  coated 
on  glass  does  not  deteriorate  so  rapidly  as  one  coated 
on  celluloid.  This  is  not  of  great  importance,  the  keep- 
ing qualities  of  films  being  good  enough  for  all  but 
very  exceptional  purposes. 

(4)  Some  plates  are  cheaper  than  films. 

(5)  During  the  summer  of  1915  the  writer  used 
film  packs  very  extensively,  making  about  thirty  dozen 
negatives  in  this  manner,  and  lost  about  ten  per  cent, 
of  the  negatives  through  streaks  of  irregular  density, 
this  fault  not  being  due  to  any  defect  of  technique,  as 
admitted  by  the  manufacturers  of  the  film,  but  being 
caused  by  defects  in  the  films.  The  makers  were  unable 
to  assign  any  cause  for  this  circumstance,  which  has 
never  occurred,  so  far  as  the  writer’s  experience  goes, 
with  either  plates  or  roll  films. 

(6)  Plates  are  easier  to  handle  during  development 
and  subsequent  manipulations  than  are  films. 

(7)  If  time  is  of  importance  plates  may  be  dried, 
after  fixing  and  washing,  by  means  of  alcohol,  which 
cannot  be  done  with  films. 

(8)  Plates  are  non-inflammable. 

The  advantages  of  films  over  plates  are: 

(1)  They  are  much  lighter  and  more  compact. 

75 


PLATES  — FILMS  — RAY-FILTERS 


(2)  They  are  unbreakable. 

(3)  All  films  are  non-halation. 

(4)  They  are  cheaper  than  some  plates. 

(5)  If  a reversed  negative  is  desired  for  carbon 
printing,  or  a reversed  positive  for  photogravure,  the 
print  may  be  made  from  the  back  of  the  film  without 
causing  any  perceptible  diffusion. 

Generally  speaking,  it  may  be  said  that  if  lightness 
and  compactness  are  of  sufficient  importance  to  justify 
the  worker  in  risking  an  occasional  failure  through  a 
defective  film  (and  these  failures  cannot  be  foreseen 
or  guarded  against)  he  should  by  all  means  use  films, 
provided  his  work  does  not  demand  double-coated  or 
panchromatic  plates,  but  if  he  wishes  to  be  certain 
that  his  apparatus  is  entirely  reliable,  and  can  afford 
the  extra  bulk  and  weight  of  plates,  he  will  do  better 
to  adhere  to  the  latter,  though  it  may  be  added  that 
the  writer,  in  his  own  work,  employs  both  films  and 
plates,  as  the  circumstances  indicate. 


CHAPTER  IV 

EXPOSURE  AND  DEVELOPMENT 

Characteristic  Curve  of  Plate. — If  successive 
portions  of  a dry  plate  be  given  progressively  increasing 
exposures  to  a standard  illumination,  and  the  plate 
be  developed  in  any  standard  developer,  the  densities 
of  the  different  portions  being  measured  (after  the  plate 
is  fixed,  washed,  and  dried)  by  means  of  a photometer, 
a curve  may  be  plotted  in  which  abscissae  represent 
light-action  and  ordinates  densities,  and  it  will  be 
found  that  the  form  of  this  curve  is  constant  for  every 
make  and  type  of  plate,  though  the  actual  dimensions 
may  vary.  This  curve  is  known  as  the  characteristic 
curve  of  the  plate,  and  is  due  to  the  classical  investi- 
gations of  Messrs.  Hurter  and  Driffield,  two  English 
scientists  who  made  a series  of  experiments  with  regard 
to  exposure  and  development,  some  years  ago.  This 
curve  is  shown  in  Figure  38,  and  it  will  be  seen  that  it 
may  be  divided  into  four  portions,  (a)  in  which  density 
increases  relatively  more  rapidly  than  light-action,  (b) 
in  which  density  and  light-action  increase  in  the  same 
ratio,  (c)  in  which  density  increases  relatively  less 
rapidly  than  light-action,  and  (d)  in  which  density 
decreases  as  light-action  increases.  The  first  corre- 
sponds to  under-exposure,  the  second  to  normal  ex- 
posure, the  third  to  over-exposure,  and  the  fourth  to 
reversal,  in  which  the  plate  develops  as  a positive 
instead  of  a negative,  this  last-named  phenomenon  being 
of  laboratory  interest  only. 


77 


P£K3mr 


EXPOSURE  AND  DEVELOPMENT 


In  order  to  make  the  meaning  of  this  curve  clear  to 
the  non-scientific  reader,  let  us  suppose  that  we  wish  to 
photograph  three  objects,  and  to  reproduce  them  in 
their  proper  relative  values,  one  of  the  objects  being 
white,  one  black,  and  the  third  of  a gray  which  is  mid- 
way between  white  and  black.  Obviously,  the  gray 
object  should  have,  in  the  negative,  such  density  that 
its  image,  in  the  print,  will  have  a value  midway  be- 
tween that  of  the  white  and  that  of  the  black  objects, 
and  this  will  be  the  case  if  the  exposure  was  what  we 


Fig.  38. 

call  normal.  If,  however,  the  exposure  was  insufficient, 
the  density  of  the  gray  object  will  be  nearer  that  of  the 
black  than  that  of  the  white,  all  the  values,  of  course, 
being  incorrectly  rendered.  On  the  other  hand,  if  the 
exposure  was  excessive  the  density  of  the  gray  object 
will  be  nearer  that  of  the  white  than  that  of  the  black, 
the  values  being  as  faulty  as  in  the  other  case,  though 
in  a different  manner.  This  may  be  understood  by 
reference  to  Figure  39,  in  which  (A)  represents  under- 
78 


CHARACTERISTIC  CURVE  OF  PLATE 


exposure,  (B)  normal,  and  (C)  over-exposure.  These 
facts  are  usually  expressed  by  saying  that  under- 
exposure flattens  the  shadows,  giving  a thin  negative 
lacking  in  shadow  detail,  and  that  over-exposure 
flattens  the  lights,  giving  a thick  negative  which 
lacks  brilliance.  Messrs.  Hurter  and  Driffield  also 
found  that  this  internal  relationship  of  values  cannot 
be  altered  by  any  modifications  of  development  or  by 
changes  in  the  composition  of  the  developer,  thus  dis- 
proving the  popular  idea  that  errors  of  exposure  may  be 


Fig.  39. 


corrected  in  development.  Curiously  enough,  this  false 
idea,  which  is  based  on  empirical  and  unscientific  obser- 
vation, still  persists  to  some  extent,  and  we  find  writers, 
even  at  the  present  day,  advocating  the  addition  of 
restrainer  in  case  of  over-exposure,  and  of  alkali  in 
under-exposure.  It  is  true  that  the  contrast  of  the 
negative  may  be  increased  by  prolonging  development 
or  decreased  by  giving  shorter  development  than  nor- 
mal, but  the  internal  relationship  (except  in  one  special 
case,  which  will  be  discussed  later)  is  fixed  once  for  all 

79 


EXPOSURE  AND  DEVELOPMENT 


by  the  exposure.  In  Figure  39  the  dotted  lines  repre- 
sent the  densities  of  the  various  gradations  with 
prolonged  development. 

Hurter  and  Driffield’s  Law. — These  facts  may 
be  expressed  in  the  form  of  a law,  as  follows: 

Relative  contrast  is  a function  of  exposure. 

Actual  contrast  is  a function  of  development. 

The  term  “actual  contrast”  of  course  refers  to  the 
separation  between  the  extremes  of  the  negative.  That 
is,  to  refer  again  to  the  illustration  of  the  three  objects, 
short  development  may  result  in  rendering  the  black 
object  as  a dark  gray  and  the  white  object  as  a light 
gray,  whereas  excessive  development  may  result  in 
extending  the  scale  of  the  negative  beyond  the  capacity 
of  any  printing  paper  to  render,  but  the  relation  of 
white,  gray  and  black  is  not  changed  by  any  variations 
in  development. 

Failure  of  Hurter  and  Driffield’s  Law. — There 
is  one  case  in  which  this  law  fails;  namely,  in  the  case 
of  relatively  brief  development  in  a very  dilute  solution. 
This  exception  to  the  law  was  noted  by  Messrs.  Hurter 
and  Driffield,  and  is  explicable  in  the  following  manner: 
When  a plate  is  exposed  on  objects  having  a range  of 
gradation  from  dark  to  light  (as  is  always  the  case  in 
pictorial  work)  the  action  of  the  light  reflected  from  the 
lighter  objects  extends  fairly  deep  into  the  film,  whereas 
the  light-action  in  the  shadows  may  be  chiefly  on  or 
near  the  surface.  When  a developer  is  applied  to  the 
plate  the  light-affected  silver  salt  on  the  surface  is 
readily  reduced  to  the  metallic  state,  but  in  order  that 
the  underlying  portions  may  be  developed  it  is  neces- 
sary that  the  reducing  agent  penetrate  deep  into  the 

80 


UNDER-  AND  OVER-EXPOSURE 


gelatine  film.  If  the  developer  is  very  dilute  a given 
volume  of  the  solution  carries  but  a small  amount  of 
reducing  agent,  and  this  readily  becomes  exhausted 
in  acting  on  the  silver  salt.  If  the  action  is  taking  place 
near  the  surface  of  the  film  the  exhausted  developer 
may  easily  be  got  out  of  the  film  and  replaced  by  fresh 
(by  rocking  the  tray),  whereas  if  it  is  going  on  deep 
within  the  film  some  time  is  required  for  the  exhausted 
agent  to  be  replaced,  and  all  the  while  the  reduction  of 
the  surface  silver  (that  is,  the  shadows)  is  proceeding. 
Hence  if  development  is  arrested  before  all  the  light- 
affected  silver  salt  has  been  reduced  to  the  metallic 
state  the  shadows  will  have  normal  density  but  the 
lights  will  have  less  than  they  should,  and  the  negative 
will  have  somewhat  the  appearance  of  over-exposure, 
though  the  variation  from  normal  will  be  very  slight. 
Therefore,  in  the  case  of  known  under-exposure  the  use 
of  a very  dilute  developer  will  tend  to  produce  better 
results  than  normal  treatment.  Of  course,  if  a strong 
developer  is  used  this  flattening  of  the  lights  does  not 
take  place,  since  the  reducing  agent  is  not  so  readily 
exhausted  within  the  film. 

Treatment  of  Under-  and  Over-exposure. — 
Although  nothing  can  be  done  to  correct  errors  of  ex- 
posure by  modifying  development,  much  can  be  done 
by  after-treatment  of  the  negative,  but  in  order  to  get 
the  full  benefit  of  such  treatment  the  development 
should  be  somewhat  different  from  the  normal.  If 
under-exposure  is  discovered  after  development  has 
commenced,  the  plate  should  be  transferred  to  a very 
dilute  developer  and  kept  there  until  all  possible  shadow 
detail  has  appeared,  or  until  the  negative  begins  to  show 

6 81 


EXPOSURE  AND  DEVELOPMENT 


fog,  regardless  of  the  quality  of  the  lights,  which,  of 
course,  will  be  far  too  dense  when  fixation  is  complete. 
The  result  will  be  a negative  which  will  probably  have 
a scale  too  great  for  any  printing  paper,  but  subsequent 
reduction  with  ammonium  persulphate,  which  attacks 
the  dense  parts  more  than  the  thin,  will  give  a nega- 
tive approaching  more  nearly  a correctly  exposed  one 
than  any  other  treatment.  If  the  plate  shows  over- 
exposure development  should  be  prolonged  in  order  to 
gain  as  much  contrast  as  possible,  the  excessively  dense 
negative  being  afterward  reduced  with  Farmer’s  re- 
ducer, which  attacks  the  shadows  before  the  lights, 
thus  getting  more  brilliance  than  would  come  from 
normal  development. 

Characteristics  of  Abnormal  Negatives. — The 
writer  has  found  that  many  persons,  even  some  who 
have  had  considerable  photographic  experience,  are 
unable  to  determine  by  inspection  whether  a negative 
is  under-exposed  or  under-developed  as  well  as  whether 
it  is  over-exposed  or  over-developed,  and  it  seems 
advisable  to  indicate  the  difference  in  appearance  of 
these  faults.  An  under-exposed  negative  will,  as  stated 
above,  be  thin  all  over — assuming  that  development 
has  been  normal — will  be  lacking  in  shadow  detail,  and 
will  show  excessive  contrast  between  the  fights  and 
the  shadows.  Under-development  will  give  a plate 
which  will  be  thin,  but  will  probably  show  some  indica- 
tions of  shadow  detail,  and  will  have  a normal  range 
of  gradation.  Over-exposure  results  in  a dense,  flat 
negative,  lacking  in  brilliance  in  the  fights,  whereas  an 
over-developed  plate,  though  dense  all  over,  will  have 
brilliance  and  contrast.  Some  little  experience  will  be 

82 


LANDSCAPE 
BY  KARL  STRUSS 
From  a Platinum  Print 


■jnyyirffMmfri  gy'y 


THE  DEVELOPER 


necessary  before  the  worker  can  distinguish  readily 
between  these  failings,  and  it  would  be  very  profit- 
able for  a young  photographer  to  make  a series  of 
experiments  in  which  under-,  normal,  and  over-expo- 
sure are  combined  with  under-,  normal,  and  over- 
development. 

Function  and  Composition  of  the  Developer. — 
Although  the  action  of  the  light  is  to  effect  a change 
in  the  sensitive  salt  contained  in  the  film,  no  change 
is  visible  until  the  plate  has  been  treated  with  a de- 
veloper, unless,  indeed,  the  exposure  be  tremendously 
excessive.  The  function  of  the  developer  is  to  reduce 
the  light-affected  salt  to  metallic  silver,  and  the  develop- 
ing solution  generally  consists  of  water,  a reducing 
agent,  a preservative,  to  keep  the  reducing  agent  from 
being  oxidized  too  rapidly  by  the  oxygen  in  the  water, 
and  an  alkali,  the  precise  effect  of  this  latter  ingredient 
not  being  accurately  known.  Some  reducing  agents, 
notably  amidol,  do  not  require  the  addition  of  an 
alkali,  but  in  general  this  ingredient  is  necessary.  There 
are  forty  or  fifty  different  reducing  agents  available, 
most  of  them  derived  from  coal-tar,  though  some  are 
obtained  from  nut-galls,  lichens,  sea-weed,  or  other 
vegetable  substances,  and  one  is  inorganic.  The  pre- 
servative most  in  use  is  sodium  sulphite,  though  citric 
acid,  potassium  metabisulphite,  and  other  chemicals  are 
sometimes  employed.  The  most  usual  alkali  is  sodium 
carbonate,  but  caustic  soda,  caustic  potash,  and  carbon- 
ate of  potash  are  also  used.  Formulae  for  different 
solutions  will  be  given  later,  together  with  a brief 
discussion  of  the  characteristics  of  the  better-known 
reducing  agents. 


83 


EXPOSURE  AND  DEVELOPMENT 


Methods  of  Development. — There  are  four 
methods  of  development,  (a)  by  inspection,  (b)  factorial, 
(c)  by  time  in  a tray  and  (d)  by  time  in  a tank.  In 
development  by  inspection  the  exposed  plate  is  taken 
from  the  holder  in  the  dark-room,  immersed  in  a tray 
of  developer,  and  rocked  until  the  worker  judges,  from 
looking  at  the  negative  by  transmitted  light  (non- 
actinic  light,  of  course)  that  development  has  pro- 
gressed far  enough  to  give  the  desired  quality  of  print. 
This  is  the  most  laborious,  most  uncertain,  and  least 
scientific  method,  besides  being  most  likely  to  result  in 
damage  to  the  negative  from  scratches  or  fog,  no  dark- 
room light  being  absolutely  safe.  Nevertheless  it  is  the 
method  most  in  use,  since  it  is  the  oldest,  and  most 
photographers,  like  other  individuals,  are  reluctant  to 
adopt  new  methods.  In  addition  to  the  other  reasons 
for  discarding  this  form  of  development,  we  may  note 
that  if  there  is  much  work  to  be  done  a very  noticeable 
reduction  of  the  worker’s  vitality  results  from  a pro- 
longed stay  in  the  dark-room,  this  reduction  sometimes 
amounting  to  two  or  three  per  cent,  in  as  many  hours. 
Some  photographers  profess  to  enjoy  dark-room  work, 
and  when  this  is  the  case  all  that  can  be  said  is  that  if 
the  worker  regards  development  as  a form  of  amuse- 
ment he  should  by  all  means  develop  by  inspection; 
but  those  photographers  who,  like  the  writer,  consider 
the  negative  merely  as  a means  to  an  end — the  print — 
will  do  well  to  adopt  some  other  method. 

The  factorial  method,  worked  out  by  Alfred  Watkins, 
depends  on  the  fact  that  for  every  reducing  agent, 
irrespective  of  the  concentration  and  composition  of  the 
developing  solution,  there  is  a definite  ratio  between 


METHODS  OF  DEVELOPMENT 


the  time  required  for  the  plate  to  gain  all  the  contrast 
possible  in  the  given  circumstances,  and  the  time 
required  for  the  image  to  make  its  appearance  after 
immersion  in  the  developer.  This  ratio  is  known  as  the 
factor,  and  there  are  but  few  exceptions  to  the  rule 
stated,  pyro  and  amidol  being  the  best-known  of  the 
agents  whose  factor  depends  on  the  strength  of  the 
solution.  Mr.  Watkins  has  determined  the  factors 
for  the  reducing  agents  most  in  use,  and  gives  the 
following  table: 


Adurol 

5 

Imogen  sulphite.  . . 

6 

Amidol  (2  grains  per  ounce) . 

18 

Kachin 

10 

Azol 

30 

Mequin 

12 

Certinal 

30 

Metol 

30 

Diogen 

12 

Ortol 

10 

Edinol 

20 

Paramidophenol.  . . 

16 

Eikonogen 

9 

Pyrocatechin 

10 

Glycin-potash 

12 

Quinomet 

30 

Glycin-soda 

8 

Rodinal 

30 

Hydroquinone 

5 

Synthol 

30 

Pyro,  no  bromide. 

Grains  of  pyro  per 
ounce  of  solution 

Factor 

1 

. . 18 

2 

. . 12 

3 

. . 10 

4 

. . 8 

5 

•• 

Azol,  certinal,  citol,  and  rodinal  are  said  to  be  the  same 
product  under  different  trade  names,  being  a concen- 
trated solution  of  paramidophenol  with  preservative 
and  caustic  alkali.  It  may  be  noted  that  in  numerous 
other  cases  different  names  represent  the  same  chemical. 
Thus,  metol  and  elon  are  said  to  be  identical  except 
that  the  former  is  put  out  by  Hauff  and  the  latter 
by  the  Eastman  Kodak  Company.  To  employ  the 
factorial  method  of  development  the  factor  to  be 

85 


EXPOSURE  AND  DEVELOPMENT 


used  in  the  specific  case  is  first  determined  (using,  of 
course,  a smaller  factor  than  the  one  given  if  less  than 
maximum  contrast  is  desired)  and  the  plate  is  immersed 
in  the  solution  in  the  dark-room,  the  tray  being  rocked 
and  the  plate  watched  until  the  image  first  begins  to 
appear.  The  time  required  for  this  first  appearance  is 
multiplied  by  the  factor  chosen,  and  the  plate  is  de- 
veloped for  the  total  time  thus  indicated.  Of  course, 
the  tray  may  be  covered  during  development,  thus 
minimizing  the  risk  of  fog.  To  take  a concrete  example, 
suppose  rodinal  is  being  used  and  a soft  negative  is 
desired.  The  factor  chosen  would  probably  be  about  20, 
depending  on  the  contrast  in  the  subject  and  the 
quality  of  the  result  to  be  obtained.  Suppose  the 
image  to  appear  in  10  seconds,  then  the  total  time  of 
development  would  be  200  seconds,  and  the  plate 
would  be  developed  for  three  minutes  and  twenty 
seconds  from  the  first  immersion,  being  fixed  and 
washed  at  the  expiration  of  the  time,  without  the  need 
for  further  examination.  This  method  represents  a 
great  advance  on  the  inspection  method,  and  is  strongly 
recommended  to  those  workers  who,  developing  only 
one  or  two  plates  at  a time,  do  not  care  to  use 
a tank. 

In  time  development  in  a tray  the  plate  is  im- 
mersed in  the  developing  solution  and  the  tray  rocked 
for  a definite  length  of  time,  this  time  depending  on  the 
composition,  strength,  and  temperature  of  the  solution 
(since  all  developers  act  more  rapidly  at  high  tempera- 
tures than  at  low  ones)  and  on  the  development  speed 
of  the  plate,  different  makes  of  plate  varying  greatly  in 
this  respect.  Only  experience  can  determine  how  long 

86 


METHODS  OF  DEVELOPMENT 


to  develop  in  order  to  get  the  desired  contrast,  but  this 
method  is  very  convenient  for  those  workers  who  are 
willing  to  make  a few  experiments  with  their  customary 
brand  of  plate,  in  the  event  of  there  being  only  one  or 
two  plates  to  develop,  and  it  is  practically  imperative 
with  panchromatic  plates.  Obviously,  there  is  no  need 
of  using  a dark-room  light  when  time  development  is 
employed,  so  that  this  forms  a very  desirable  method 
when  travelling,  since  any  room  can  be  used  as  a dark- 
room at  night. 

Tank  development  is  the  same  as  time  develop- 
ment, except  that  a water-tight  tank  is  used,  a number 
of  plates  being  placed  in  a rack  in  the  tank,  so  that  they 
are  kept  vertical,  and  that  a weak  developer  is  em- 
ployed, with  the  result  that  development  requires  from 
fifteen  minutes  to  an  hour,  depending  on  circumstances. 
Tank  development  is  economical  of  time,  since  a dozen 
or  more  plates  may  be  developed  at  once,  obviates  all 
danger  of  fog  or  scratching,  and  automatically  gives 
the  best  quality  of  negative  from  any  given  subject 
and  exposure,  since  slow  development  in  a dilute  solu- 
tion is  nearly  always  preferable  to  rapid  development. 
Care  must  be  taken  to  see  that  the  tank  is  kept  free 
from  dirt  or  undesirable  chemicals,  and  it  should  be  of  a 
type  having  a cover  which  locks  on,  so  that  the  tank 
may  be  inverted  at  intervals,  since  if  it  remains  always 
in  one  position  the  developer  will  settle,  giving  greater 
density  at  one  end  of  the  negatives  than  at  the  other. 
It  is  also  well  to  have  the  tank  so  arranged  that  the 
developer  may  be  poured  in  and  out  after  the  plates 
are  in  place,  since  in  this  case  a dark-room  is  neces- 
sary only  for  loading  'the  plates  into  the  tank, 

87 


EXPOSURE  AND  DEVELOPMENT 


development  and  fixation  being  carried  out  in  full 
daylight. 

Characteristics  of  Various  Developers. — 
Despite  the  claims  of  some  manufacturers,  there  is  no 
difference  among  the  numerous  reducing  agents,  so  far 
as  the  power  of  giving  density  and  detail  are  concerned 
or  as  regards  inherent  fog-producing  tendency.  There 
is,  however,  great  difference  in  the  speed  of  working, 
and  in  the  manner  of  doing  the  work.  It  will  be  seen 
from  the  table  on  page  85  that  reducing  agents  may 
be  divided  into  two  broad  classes,  those  having  short 
factors  and  those  having  long  ones,  and  it  has  been 
found  that  the  latter  tend  to  bring  out  the  image  all 
over  the  plate  early  in  the  process,  lights,  half-tones, 
and  shadows  nearly  simultaneously,  the  density  growing 
subsequently,  whereas  the  agents  having  short  factors 
bring  out  the  lights  first,  and  after  these  have  gained 
some  density  the  half-tones  appear,  both  lights  and 
half-tones  growing  in  density  for  some  time,  the  shadows 
finally  making  their  appearance.  From  this  it  will  be 
seen  that  if  a soft,  fully  detailed  negative  is  desired  it  is 
best  to  choose  a long-factor  developer,  such  as  rodinal 
or  metol,  whereas  if  considerable  contrast  is  wanted  a 
short-factor  one,  e.g.9  strong  pyro  or  hydroquinone,  is 
to  be  preferred,  so  that,  although  a short-factor  de- 
veloper may  be  made  to  give  a soft  negative  by  develop- 
ment in  a dilute  solution,  or  a long  factor  agent  may  be 
made  to  give  contrast  by  prolonged  development  in  a 
concentrated  solution,  convenience  dictates  that  the 
agent  be  chosen  with  regard  to  the  work  to  be  done. 
This  relation  between  manner  of  working  and  length 
of  factor  seems  to  have  no  scientific  basis,  being  purely 

88 


VARIOUS  DEVELOPERS 


empirical,  but  it  will  be  found  generally  true,  the  chief 
exception  being  eikonogen,  which  has  a relatively  short 
factor  but  tends  to  give  soft  negatives. 

For  the  sake  of  convenience,  the  developer  should 
be  capable  of  being  made  up  in  the  form  of  a concen- 
trated solution,  requiring  only  dilution  with  water  to 
be  ready  for  use,  and  should  keep  well  when  so  made 
up.  It  should  also  work  satisfactorily  when  used  for 
several  plates  in  succession,  and  if  the  used  developer 
can  be  kept  and  employed  on  subsequent  days  this 
is  an  additional  advantage.  There  are  several  agents 
which  fulfil  these  requirements,  and  formulae  are 
given  below. 


Metol-Hydroquinone. 

Water,  distilled,  warm 16  ounces 

Metol 96  grains 

Hydroquinone 384  grains 

Dissolve  and  add 

Sodium  sulphite  (anhydrous) 1310  grains 

Stir,  and  when  the  sulphite  is  dissolved  there  will  be  a 
thick  white  precipitate. 

Add 

Caustic  soda  (pure  stick) 256  grains 

When  the  alkali  is  dissolved  the  solution  will  be  clear. 
Filter  into  a bottle.  For  use  take 

Stock 1 ounce 

Water 10  to  30  ounces. 

Factor  about  16. 

Edinol. 

Water,  distilled,  warm 14  ounces 

Potassium  metabisulphite 300  grains 

Sodium  carbonate  (anhydrous) 800  grains 

Grind  these  two  salts  together  intimately  in  a mortar  and 
dissolve  a little  at  a time. 

Add 

Edinol 300  grains 

When  dissolved  filter  into  a bottle.  For  use  take 

Stock.... 1 ounce 

Water 10  to  30  ounces 


Factor  20.  Hot  water  must  not  be  used  or  the  metabisulphite 
will  be  decomposed. 


89 


EXPOSURE  AND  DEVELOPMENT 


Eikonogen  cannot  well  be  made  up  in  the  form  of  a 
concentrated  solution,  but  it  is  an  excellent  developer, 
and  a formula  follows : 


A.  Water,  distilled 30  ounces 

Sodium  sulphite  (anhydrous) 480  grains 

Eikonogen . 240  grains 

B.  Water,  distilled 30  ounces 

Sodium  carbonate  (anhydrous) 360  grains 

Use 

A 1 ounce 

B 1 ounce 

Water 0 to  1 ounce 

Factor  S. 


Rodinal  is  very  convenient,  being  sold  in  the  form  of 
a concentrated  solution,  requiring  only  dilution  for  use. 


Use 

Rodinal 1 ounce 

Water 10  to  30  ounces 


Factor  30. 


Rytol  is  also  very  convenient,  and  is  especially 
recommended  for  use  when  travelling,  since  it  is  sold 
in  the  form  of  tablets,  which  are  to  be  dissolved  in 
water  for  use,  hence  it  can  do  no  damage  if  the  bottle 
is  accidentally  broken. 

Use 

Rytol,  one  pair  of  products 

Water 4 to  12  ounces 

Factor  12  to  18. 


Practically  all  the  desirable  developers  can  be  obtained 
in  tablet  form,  but  the  writer  prefers  rytol,  not  because 
it  is  better  than  the  others,  but  because  it  is  cheaper 
than  most.  Pyro  is  a popular  agent,  but  has  many 
disadvantages  as  compared  to  the  newer  organic  de- 
velopers, in  that  it  does  not  keep  well  in  solution  unless 
special  precautions  are  taken,  that  it  cannot  be  used 
repeatedly,  and  that  it  tends  to  stain  plates  and  fingers 
90 


VARIOUS  DEVELOPERS 


badly.  The  writer  uses  it  only  for  tank  development, 
when  these  objections  disappear  if  the  solution  is  made 
fresh  at  the  time  of  use.  Two  formulae  follow: 

Pyro  for  Wratten  panchromatic  plates  (8X10  tank). 


Tap  water 150  ounces 

Sodium  sulphite  (anhydrous) 405  grains 

Sodium  carbonate  (anhydrous) 135  grains 

Pyro i 135  grains 


Development  time  one-half  to  three-fourths  that  given  on 
the  speed  card  packed  with  plates. 


Pyro  for  Eastman  film. 

Tap  water 50  ounces 

Sodium  sulphite  (anhydrous) 90  grains 

Sodium  carbonate  (anhydrous) 00  grains 

Pyro 30  grains 


Development  time  20  minutes  at  65°  Fahrenheit. 


As  stated  above,  all  developers  work  more  rapidly 
when  warm  than  when  cold,  and  the  ideal  temperature 
is  65°  Fahrenheit,  it  being  of  especial  importance  to 
maintain  a definite  temperature  when  developing  by 
time.  Some  agents,  especially  hydroquinone,  work  with 
impractical  slowness  at  low  temperatures,  and  if  the 
solution  goes  above  70°  Fahrenheit  there  is  always 
danger  of  frilling;  that  is,  loosening  of  the  film  from 
the  glass.  Therefore,  a thermometer  should  be  part  of 
the  equipment  of  every  dark-room. 


CHAPTER  V 

MISCELLANEOUS  APPARATUS 

Actinometers  and  Exposure  Tables. — There  are 
three  methods  of  determining  the  correct  exposure  in 
any  given  circumstances:  first,  by  past  experience; 
second,  by  the  use  of  an  actinometer  which  measures 
the  intensity  of  the  light  falling  upon  the  subject;  and 
third,  by  the  use  of  an  exposure  table  which  gives  the 
correct  exposure  for  different  subjects  with  different 
conditions  of  light,  lens  stop  and  plate  speed.  The 
first  method  is  not  recommended,  since  it  requires 
considerable  experience  and  is  at  best  uncertain,  even 
practised  photographers  often  going  astray.  Either  of 
the  other  methods  is  satisfactory,  but  must  be  used 
with  judgment,  since  neither  is  absolutely  accurate  in 
all  circumstances.  There  are  two  types  of  actinometer, 
the  first  depending,  as  in  the  instruments  of  Wynne 
and  Watkins,  on  the  time  required  for  a piece  of  sensi- 
tive paper  to  darken  to  match  a standard  tint,  the 
second,  as  in  the  case  of  the  Heyde  meter,  depending 
on  the  progressive  obscuring  of  shadow  details  as  vary- 
ing thicknesses  of  tinted  glass  are  placed  between  the 
eye  and  the  object  to  be  photographed.  Any  of  the 
instruments  named  will  be  found  satisfactory  for 
general  use,  but  they  will  tend  to  call  for  unnecessarily 
long  exposure  when  used  in  a weak  light,  such  as  that 
of  late  afternoon  or  indoors.  There  are  a number  of 
different  exposure  tables  on  the  market,  such  as  those 
given  in  the  various  photographic  magazines,  the 

92 


SHUTTERS 


Harvey  meter  (which  is  really  an  exposure  table)  the 
Burroughs  Wellcome  note-book  and  others.  The 
writer’s  experience  shows  that  all  of  these  are  quite 
reliable,  but  indicates  that  the  Burroughs  Wellcome 
note-book  is  the  most  convenient  form,  this  possessing 
not  only  completeness  and  accuracy  combined  with 
compactness,  but  also  furnishing  a Space  for  recording 
data  concerning  exposures,  such  as  the  serial  number 
of  the  negative,  the  kind  of  plate  used,  the  lens  aper- 
ture, the  character  of  the  light,  the  time  of  day  and  of 
year,  and  the  exposure  given.  It  is  strongly  recom- 
mended that  this  information  be  recorded  with  every 
exposure,  at  all  events  until  the  photographer  has 
gained  considerable  experience,  since  reference  to  it 
from  time  to  time  will  aid  notably  in  developing  the 
judgment.  It  will  be  found  that  exposure  tables  as 
well  as  actinometers  fail  in  a weak  light,  but  with 
exposure  tables  the  failure  is  due  to  a tendency  to 
indicate  insufficient  exposure  and  also  to  the  fact  that 
it  is  difficult  to  estimate  visually  the  quality  of  the 
light  when  this  is  relatively  weak;  that  is,  although 
it  is  easy  enough  to  see  whether  it  is  intense  or  slightly 
veiled,  it  is  difficult  to  tell  whether  it  should  be  classed 
as  dull  or  very  dull. 

Shutters. — There  are  numerous  types  of  shutter, 
each  being  especially  adapted  for  some  particular  pur- 
pose, the  simplest  method  of  making  an  exposure  being 
with  the  lens  cap,  which  is  perfectly  satisfactory  when 
exposures  of  less  duration  than  a quarter  of  a second 
are  not  desired.  The  between-lens  shutter  is  good  for 
general  purposes,  but  is  not  made  for  large  lenses,  and 
the  cheaper  grades  cannot  be  depended  on  for  accuracy 

93 


MISCELLANEOUS  APPARATUS 


at  the  higher  speeds,  the  variation  from  the  marked 
speed  being  often  100  per  cent,  or  more.  The  more 
expensive,  as  the  Koilos,  Compound,  Goerz  or  Multi- 
speed, are  usually  fairly  accurate,  but  any  between-lens 
shutter  is  relatively  inefficient  at  high  speeds,  owing  to 
the  fact  that  the  lens  is  not  working  at  full  aperture 
during  the  entire  time  of  exposure,  since  the  leaves  of 
the  shutter  require  a perceptible  interval  to  open  and 
close.  For  rapid  exposures  the  focal  plane  shutter  will 
be  found  more  efficient,  since  this  consists  of  a strip  of 
cloth  having  slits  the  full  length  of  a plate  and  of  vary- 
ing width,  operating  immediately  in  front  of  the  plate, 
so  that  the  full  aperture  is  available  during  the  entire 
time  of  exposure.  Different  speeds  are  obtainable  by 
varying  the  width  of  the  slit  or  the  tension  of  the  spring 
or  both,  so  that  the  curtain  travels  across  the  plate  at 
varying  rates  of  speed  or  permits  the  passage  of  only 
a narrow  band  of  light  during  a given  interval.  The 
most  desirable  form  of  this  type  of  shutter  is  the  one 
in  which  the  curtain  consists  of  a long  strip  of  cloth 
with  different  sized  slits,  rather  than  the  one  in  which 
the  width  of  the  slit  is  variable,  since  the  latter  is  more 
likely  to  get  out  of  order  and  give  a slit  wider  at  one 
end  than  the  other,  thus  giving  more  exposure  to  one 
side  of  the  plate  than  to  the  other.  The  roller  blind 
shutter  resembles  the  focal  plane  type  in  that  the 
exposure  is  made  by  the  travel  of  a curtain  having  an 
opening  in  it,  but  it  is  usually  placed  immediately  before 
or  behind  the  lens  instead  of  near  the  plate,  and  has  but 
one  slit  (the  width  of  which  is  equal  to  or  exceeds  the 
full  aperture  of  the  lens),  the  speeds  being  controlled 
entirely  by  the  tension  of  the  spring.  This  type  of 
94 


OTHER  APPARATUS 


shutter  is  fairly  efficient  and  is  simple  and  not  likely 
to  get  out  of  order,  but  as  sent  out  by  the  makers  is 
not,  as  a rule,  accurately  marked  for  speed,  wherefore 
the  speeds  should  be  tested  if  precision  is  desired.  There 
are  numerous  forms  of  studio  shutter,  the  chief  desid- 
eratum in  this  instance  being  noiseless  operation,  and 
the  best  shutter  of  this  form  known  to  the  writer  is 
that  in  which  the  leaves  of  the  shutter  form  the  dia- 
phragm of  the  lens,  exposure  being  made  by  the  open- 
ing and  closing  of  these  leaves.  This  shutter  is  rela- 
tively slow  as  compared  to  other  types,  for  the  most 
rapid  exposure  obtainable  with  it  is  about  1/8  second, 
whereas  the  between-lens  shutter  will  give  from  1/100 
to  1/300  (the  Multispeed  is  said  to  give  1/2000),  the 
focal  plane  will  give  about  1/1000  and  the  roller  blind 
about  1/75.  Of  course  these  high  speeds  are  not 
necessary  for  indoor  work,  where  an  exposure  of  less 
than  1/8  second  is  practically  never  desired. 

Other  Apparatus. — Every  worker  will  determine 
for  himself  what  is  required  in  the  way  of  general 
apparatus,  but  a few  suggestions  may  be  given.  As 
regards  trays,  those  made  of  hard  rubber  are  probably 
the  best  for  general  purposes,  but  are  also  the  most 
expensive  and  are  somewhat  fragile.  Porcelain  and 
glass  trays  are  also  good,  but  are  liable  to  be  broken 
unless  carefully  handled.  The  porcelain-lined  steel  trays 
are  not  open  to  these  objections  and  are  very  desirable, 
though  it  sometimes  happens  that  the  enamel  is  chipped 
off  and  the  metal  exposed,  which  of  course  interferes 
with  their  usefulness,  since  many  solutions  are  injured 
by  contact  with  the  steel.  In  such  a case  a touch  of 
asphaltum  varnish  will  often  repair  the  damage  satis- 

95 


MISCELLANEOUS  APPARATUS 


factorily.  Japanned  paper  trays  are  good  as  well  as 
cheap  and  are  not  readily  broken,  but  the  japan  some- 
times cracks,  in  which  case  the  asphaltum  varnish  may 
be  requisitioned.  Japanned  metal  trays  are  not  desir- 
able, since  the  japan  flakes  off  very  readily. 

Developing  tanks  should  be  of  brass  nickel-plated, 
in  which  case  they  may  be  used  for  fixing  a s well  as 
developing,  provided  they  are  kept  clean  and  acid 
hypo  is  not  used,  since  the  acid  will  attack  the  metal. 
Zinc  developing  tanks  should  not  be  employed,  as  these 
are  attacked  by  plain  hypo  and  can  be  used  only  for 
developing.  The  writer’s  own  practice  is  to  develop, 
fix,  and  wash  without  removing  the  plates  from  the 
tank,  washing  being  accomplished  by  putting  a hose 
clear  to  the  bottom  of  the  tank  beside  the  rack  of 
plates  and  allowing  the  water  to  flow  for  half  an  hour 
or  an  hour.  Obviously,  if  the  plates  are  washed  free 
from  hypo  the  same  will  be  the  case  with  the  tank. 
Should  it  be  desired,  however,  to  use  separate  tanks 
for  fixing  and  washing  it  will  be  found  that  hard  rubber 
is  best  for  the  former  purpose,  since  electrose  tanks  will 
be  bulged  out  of  shape  in  time  by  the  weight  of  the 
solution  in  them,  whereas  this  does  not  take  place  with 
hard  rubber.  Most  of  the  washing  boxes  on  the  market 
are  made  of  zinc  and  the  seams  open  in  time,  and  in 
addition  to  this  the  design  is  usually  such  that  the 
water  enters  at  the  bottom  and  drains  off  at  the  top, 
this  being  the  reverse  of  the  proper  method,  for  hypo 
is  heavier  than  water  and  tends  to  sink.  Should  the 
worker  wish  to  use  a special  washing  box  for  his  plates 
he  will  do  well  to  have  one  made  of  heavy  wood  with 
two  or  three  coats  of  asphaltum  varnish,  a hole  being 

96 


OTHER  APPARATUS 


placed  at  one  end  at  the  bottom  and  the  water  being 
allowed  to  enter  at  the  top.  Films  are  most  con- 
veniently washed  by  pinning  them  to  sticks  and  allow- 
ing them  to  float  for  half  an  hour  or  so  in  a bath  tub 
or  bucket,  since  by  this  means  the  hypo  readily  drains 
out  of  the  emulsion  and  sinks  to  the  bottom  of  the  water. 

Printing  frames  should  be  substantially  made  and 
should  preferably  be  of  the  two-thirds  opening  type, 
since  this  affords  better  opportunity  for  examining 
the  print.  It  is  well  to  have  one  or  two  frames  of  a 
size  larger  than  the  largest  negative  to  be  printed  from 
and  to  have  these  fitted  with  1/8  or  3/16  inch  plate 
glass,  since  it  is  necessary  in  multiple  carbon  work  to 
cut  the  tissue  larger  than  the  negative,  and  in  multiple 
gum  printing  it  is  convenient  to  do  likewise  with  the 
printing  paper.  A retouching  desk  will  be  found  con- 
venient, not  only  for  pencil  work  on  the  negative  but 
also  for  spotting  out  pin-holes,  and  the  opening  in  the 
desk  should  preferably  be  large  enough  to  afford  a view 
of  the  entire  negative.  As  to  pencils,  brushes  and 
spotting  mediums,  little  can  be  said  except  that  the 
magazine  pencils  are  the  most  convenient,  that  the 
best  brushes  are  the  small  Japanese  paint  brushes  and 
that  moist  water  colors,  though  very  desirable  for 
spotting  prints,  are  not  as  good  for  spotting  negatives 
as  the  opaque  which  is  furnished  for  this  express  purpose. 


7 


PART  II 


NEGATIVE  MODIFICATIONS 


CHAPTER  VI 

MANIPULATION  OF  NEGATIVES 

Manipulation  of  the  Negative. — It  sometimes 
happens  that  the  worker,  either  through  failure  in 
judgment  or  through  exceptional  conditions,  does  not 
succeed  in  obtaining  the  precise  quality  of  negative 
desired,  in  which  case  much  may  be  done  to  improve 
matters  by  either  intensification  or  reduction.  Also  it 
not  infrequently  occurs  that  the  relative  values  in  the 
negative  are  not  such  as  to  give  the  best  pictorial  effect, 
even  though  they  may  be  a correct  rendering  of  the 
gradations  in  the  original  subject.  In  this  case  local 
intensification  or  reduction  may  advantageously  be  em- 
ployed or  the  values  may  be  improved  by  working 
with  a pencil  on  either  the  front  or  the  back  of  the  plate, 
if  the  surface  has  been  prepared  so  as  to  take  the 
pencil  well. 

Intensification. — There  are  many  different  inten- 
sifiers  available,  some  of  them  useful  and  others  dis- 
tinctly undesirable,  so  it  may  be  well  to  indicate  what 
the  characteristics  of  an  intensifier  should  be. 

In  the  first  place,  it  should  be  capable  of  absolute 
control;  that  is,  it  should  give  either  slight  or  great 
intensification,  as  may  be  desired.  Second,  it  should 
be  capable  of  being  made  up  in  a single  solution  which 
will  keep  well  both  before  and  after  using.  Third,  it 
should  not  cause  stains  when  handled  with  ordinary 
care.  Fourth,  it  should  give  a deposit  approximating 
in  color  that  of  the  negative,  that  is,  a neutral  black  or 

101 


MANIPULATION  OF  NEGATIVES 


a warm  black,  since  if  it  gives  either  a yellow  or  a red 
color  it  will  be  difficult  to  judge  by  inspection  the 
degree  of  intensification.  Fifth,  the  intensification 
should  be  permanent.  There  are  two  intensifies 
which  fulfil  these  requirements  admirably;  namely, 
the  mercuric  bromide  and  the  mercuric  iodide  in- 
tensifies, although  these  vary  somewhat  in  their 
method  of  use  and  in  the  character  of  the  results 
obtained.  Mercuric  bromide  intensifier  is  made  up  as 
follows : 


Water 16  ounces 

Mercuric  chloride 150  grains 

Potassium  bromide. 150  grains 


The  negative  should  be  washed  free  from  hypo  and 
the  intensifier  may  be  applied  at  any  time  thereafter, 
either  before  or  after  drying  the  plate.  The  negative 
is  immersed  in  this  solution  until  it  is  completely 
bleached  and  is  then  washed  in  running  water  for  about 
half  an  hour.  After  washing  it  is  blackened  in  a solu- 
tion of  sodium  sulphite,  the  strength  of  which  is  not 
very  material,  although  10  per  cent,  is  a good  standard. 
After  blackening  it  is  washed  for  half  an  hour  and  is 
then  gently  swabbed  with  a tuft  of  cotton,  rinsed  and 
dried.  The  bleaching  solution  may  be  used  repeatedly 
until  exhausted.  This  intensifier  tends  to  reduce 
slightly  the  very  thin  portions  of  the  negative  at  the 
same  time  that  it  intensifies  the  half  tones  and  lights, 
for  which  reason  it  is  recommended  in  the  case  of  a 
negative  which  has  been  slightly  over-exposed  and 
under-developed.  The  increase  in  density  in  the  lights 
is  about  40  per  cent,  and  if  desired  the  operation  may 
be  repeated  with  a slight  further  increase  in  contrast. 

102 


INTENSIFICATION 


Some  writers  recommend  giving  the  negative  three  or 
four  minutes  in  each  of  two  acid  baths  consisting  of 


Water 10  ounces 

Hydrochloric  acid 1 dram 


these  acid  baths  to  be  applied  after  the  plate  has  been 
washed  from  the  bleacher  for  10  or  15  minutes  and  to 
be  followed  by  10  or  15  minutes  further  washing  be- 
fore blackening.  The  writer,  however,  has  not  found 
that  this  treatment  with  acid  is  of  any  practical  ad- 
vantage, though  it  may  be  so  on  theoretical  grounds, 
and  at  any  rate  it  can  do  no  harm.  It  will  be  seen  that 
the  increase  in  contrast  with  this  intensifier  is  prac- 
tically a fixed  quantity,  for  although  it  is  possible 
to  arrest  either  bleaching  or  blackening  before  it  is 
complete,  so  doing  is  likely  to  result  in  irregular 
intensification. 

The  mercuric  iodide  intensifier  is  made  up  as 
follows : 


(A)  Water,  distilled,  hot 14  ounces 

Mercuric  chloride 300  grains 

(B)  Water,  distilled 7 ounces 

Potassium  iodide 840  grains 


Allow  A to  cool  and  pour  B into  A slowly  while 
stirring.  At  first  a thick  orange-colored  precipitate  is 
formed,  but  with  further  addition  of  the  iodide  solution 
this  precipitate  is  dissolved  and  a clear  solution  of  slightly 
yellowish  tinge  results.  This  forms  the  stock  solution  and 
may  be  used  either  concentrated  or  diluted  with  three  or 
four  volumes  of  water,  both  the  concentrated  and  dilute 
solutions  keeping  well  after  using  as  well  as  before. 
The  diluted  form  is  preferable,  since  the  action  is  more 
under  control  and  also  for  the  reason  that  the  con- 

103 


MANIPULATION  OF  NEGATIVES 


centrated  solution  often  has  a tendency  to  soften 
the  gelatine  film,  causing  at  times  serious  frilling  and 
even  in  extreme  cases  complete  loosening  of  the  gela- 
tine from  the  glass.  Should  it  be  desired  to  use  the 
strong  solution  the  negative  should  be  given  10  minutes 
in  a 1 to  10  formaldehyde  bath  and  be  washed  and 
dried  before  intensifying.  This  intensifier  may  be  ap- 
plied to  the  negative  when  the  latter  is  either  wet  or 
dry  and  it  is  not  strictly  necessary  to  have  the  hypo 
completely  out  of  the  film  before  intensifying,  although 
this  is  desirable.  The  plate  to  be  intensified  is  im- 
mersed in  the  intensifying  solution,  the  tray  being 
rocked  constantly,  and  the  gain  in  density  is  watched 
until  it  has  reached  the  desired  point,  which  can  be 
clearly  determined  after  a little  experience.  The 
negative  is  then  removed  from  the  tray  and  washed  for 
ten  minutes  in  running  water,  where  it  will  assume  a 
distinctly  yellow  color.  Some  writers  recommend  the 
use  of  acid  baths  in  this  case  as  well  as  in  the  case  of 
the  mercuric  bromide  intensifier,  but  the  writer  has  not 
found  this  treatment  necessary.  After  washing,  the 
plate  may  be  dried  if  time  is  of  importance,  but  in  this 
case  the  intensification  will  gradually  fade  and  for 
stable  intensification  the  plate  should  be  blackened 
in  any  standard  developer,  when  the  intensification 
will  be  practically  permanent.  After  blackening,  the 
negative  should  be  washed  for  half  an  hour  in  running 
water  and  be  swabbed  with  a tuft  of  cotton  and  rinsed 
before  being  put  to  dry.  This  intensification  strengthens 
all  the  gradations  in  due  progression,  the  maximum 
increase  possible  being  about  70  per  cent.,  and  sub- 
sequent treatment  or  longer  treatment  is  of  no  ad- 
104 


REDUCTION 


vantage,  though  if  intensification  has  been  arrested 
before  the  maximum  increase  was  obtained  the  operation 
may  be  completed  at  any  time  afterward. 

Should  local  intensification  be  desired  the  mercuric 
iodide  intensifier  is  the  more  desirable,  since  the  in- 
crease of  density  can  be  determined  directly  by  examina- 
tion. For  this  purpose  it  should  be  applied  in  dilute 
form  with  a tuft  of  cotton  or  soft  camel-hair  brush,  the 
negative  having  previously  been  soaked  for  an  hour  in 
water.  Subsequent  manipulations  are  the  same  as  with 
general  intensification. 

There  are  other  intensifies  which  will  give  greater 
contrast  than  the  mercuric  iodide,  notably  the  Welling- 
ton silver  intensifier,  especially  if  this  be  repeated  or 
followed  by  mercuric  bromide,  but  for  practical  pur- 
poses the  mercuric  iodide  ’will  be  found  to  give  as  much 
intensification  as  is  likely  to  be  desired. 

Reduction. — There  are  three  methods  of  reduction, 
which  show  different  characteristics.  Farmer’s  reducer 
tends  to  attack  the  shadows  first,  effecting  considerable 
reduction  in  the  thin  portions  of  the  negative  before  the 
lights  are  greatly  affected.  It  is  therefore  desirable  in 
the  case  of  negatives  which  have  been  over-exposed 
and  are  so  dense  as  to  print  slowly,  without  having  the 
desired  contrast.  Ammonium  persulphate,  on  the  other 
hand,  attacks  the  denser  parts  first,  so  that  considerable 
reduction  of  contrast  may  result  before  the  shadows 
have  been  perceptibly  attacked,  and  it  is  therefore 
advised  in  the  case  of  negatives  which  have  been  under- 
exposed and  over-developed,  as  was  indicated  in 
Chapter  IV.  There  is  a third  reducer,  potassium  per- 
manganate,which  attacks  the  deposit  of  silver  uniformly, 

105 


MANIPULATION  OF  NEGATIVES 


decreasing  density,  but  neither  increasing  nor  decreas- 
ing contrast.  It  will  be  apparent  that  since  reduction 
is  actually  a process  of  solution  of  the  silver  image, 
caution  must  be  exercised  in  the  operation,  for  a deposit 
that  has  been  dissolved  out  can  never  be  restored. 
These  reducers  will  all  be  found  to  work  slowly  and 
clearly  without  risk  of  stain  or  irregular  reduction 
provided  the  directions  are  followed. 

To  employ  Farmer’s  reducer  two  stock  solutions 
should  be  made  up,  the  first  being 


Water 10  ounces 

Potassium  ferricyanide 1 ounce 

The  second  is 

Water . 10  ounces 

Hypo 1 ounce 


These  solutions  will  keep  indefinitely,  but  it  should  be 
noted  that  after  mixing  they  keep  only  a few  minutes 
and  that  the  ferricyanide  solution  should  be  kept  in 
the  dark.  The  negative  to  be  reduced  should  be  free 
from  hypo  (or  irregular  reduction  may  result)  and 
should  be  soaked  in  water  for  one  hour  before  reduction. 
The  working  solution  is  made  up  in  the  proportions  of 


Hypo  solution 1 ounce 

Ferricyanide  solution 1 dram 


and  the  negative  is  immersed  in  this  in  a tray,  preferably 
a white  porcelain  or  porcelain-lined  one,  since  this 
facilitates  watching  the  process  of  reduction,  the  tray 
being  rocked  continuously.  The  negative  is  examined 
from  time  to  time  by  transmitted  light,  and  should  be 
rinsed  before  holding  it  up  for  examination  or  streaks 
will  probably  result.  When  reduction  is  complete  the 
negative  is  washed  for  half  an  hour  in  running  water 
106 


REDUCTION 


and  set  up  to  dry.  The  deterioration  of  this  reducer 
becomes  evident  by  a change  in  color  from  lemon 
yellow  to  pale  green,  after  which  it  is  useless  and  must 
be  replaced  by  fresh. 

To  reduce  with  ammonium  persulphate,  the  nega- 
tive should  be  free  from  hypo  and  should  be  soaked  in 
water  for  one  hour  before  treatment.  The  ammonium 
persulphate  solution  should  preferably  be  made  up 
fresh  at  the  time  of  using,  although  a 10  per  cent, 
solution  will  keep  satisfactorily  if  made  with  distilled 
water  and  closely  stoppered.  The  working  solution  is 
made  up  as  follows: 


Water 2 ounces 

Ammonium  persulphate 20  grains 

Sulphuric  acid  C.  P 1 minim 


The  wet  negative  is  placed  in  this  solution  and  the  tray 
rocked  until  sufficient  reduction  has  taken  place,  when 
the  action  of  the  reducer  is  arrested  by  transferring 
the  plate  to  a 5 per  cent,  solution  of  sodium  sulphite, 
the  plate  being  subsequently  washed  for  half  an  hour 
in  running  water  and  set  up  to  dry.  It  is  advised  not 
to  keep  the  plate  in  this  reducer  for  more  than  five 
minutes  or  uneven  reduction  may  result.  If  sufficient 
reduction  has  not  taken  place  in  this  time  the  plate 
should  be  rinsed  and  transferred  to  a fresh  bath. 

There  are  several  methods  of  employing  the  potas- 
sium permanganate  reducer,  probably  the  most  reliable 
being  as  follows.  The  well-soaked  negative  is  im- 
mersed for  not  more  than  1J4  minutes  in  a bath  of 


Water,  distilled 20  ounces 

Potassium  permanganate 5 grains 


It  is  then  rinsed  in  several  changes  of  water  and  trans- 
ferred to  a 10  per  cent,  hypo  solution  for  three  or  four 

107 


MANIPULATION  OF  NEGATIVES 


minutes,  afterward  being  washed  for  half  an  hour  in  run- 
ning water  and  set  up  to  dry.  Should  the  reduction  be 
insufficient  the  operation  may  be  repeated.  If  the 
plate  shows  a yellow  stain  after  reduction,  this  may  be 
removed  by  a few  seconds’  immersion  in  a bath  of 


Water 5 ounces 

Hydrochloric  acid  C.  P 20  minims 


this  bath  being  applied  after  the  plate  is  washed  and 
being  followed  by  slight  rinsing  before  drying. 

If  local  reduction  is  to  be  effected  it  is  best  to  soak 
the  plate  for  an  hour  in  a bath  of 

Water 10  ounces 

Hypo 2 ounces 

and  apply  Farmer’s  reducer  with  a tuft  of  cotton. 
This  action  should  be  carefully  watched  and  the  plate 
rinsed  from  time  to  time,  the  object  of  soaking  in  hypo 
solution  instead  of  water  being  to  diminish  the  likeli- 
hood of  the  reduced  portion  showing  a sharp  outline, 
and  if  it  is  desired  to  follow  a definite  line  with  the 
reducer  (which, however,  is  not  generally  recommended), 
the  reducer  should  be  applied  to  the  dry  negative  with 
a fine  camel-hair  or  sable  brush. 

Retouching  on  the  Film. — It  is  sometimes  neces- 
sary to  raise  the  value  of  small  areas,  as  in  touching 
out  freckles  in  a portrait,  and  this  is  best  done  on  the 
film  when  the  lightening  required  is  not  great.  Ordi- 
narily a pencil  will  not  take  freely  on  the  film  unless 
this  has  been  especially  treated,  though  in  the  case  of 
an  intensified  negative  it  will  sometimes  do  so.  There 
are  many  retouching  mediums  on  the  market,  but  the 
best  which  the  writer  knows  is  that  for  which  the 
108 


THE  DANCE 

BY  EDWARD  R.  DICKSON 
From  a Platinum  Print 


RETOUCHING  ON  THE  FILM 


formula  is  given  in  the  manual  of  the  G.  Cramer  Dry 
Plate  Company,  this  being  as  follows: 

Turpentine 4 ounces 

Rosin 120  grains 

It  is  not  necessary  to  use  especially  pure  rosin  and 
turpentine,  the  commercial  article  being  quite  satis- 
factory. The  rosin  is  dissolved  in  the  turpentine  and 
the  medium  is  applied  to  the  film  with  a piece  of  lintless 
cloth,  a very  slight  amount  being  necessary.  The 
cloth  should  be  merely  dampened  and  the  film  rubbed 
with  it,  but  it  is  desirable  to  continue  the  rubbing  until 
the  medium  is  dry  (which  is  a matter  of  a few  seconds 
only),  as  if  this  is  not  done  the  negative  will  probably 
show  a definite  outline  where  the  medium  has  been 
applied,  this  being  especially  true  of  an  intensified 
plate.  One  application  of  this  medium  will  give  suffi- 
cient tooth  to  permit  of  considerable  work  with  an 
HB  or  a B pencil,  although  if  more  tooth  is  required 
it  is  necessary  to  use  a greater  amount  of  rosin  in  the 
medium.  If  the  work  proves  unsatisfactory  it  is  easy 
to  clean  the  pencil  marks  off  by  means  of  a cloth  damp- 
ened in  the  medium,  when  the  work  may  be  done  over 
again.  It  is  desirable  to  have  a long  point  to  the  pencil 
and  this  point  in  general  should  be  kept  very  fine,  a 
piece  of  number  0 sand-paper  being  useful  for  sharp- 
ening the  pencil.  It  is  not  necessary  to  practice  any  of 
the  special  marks  used  by  professional  retouchers,  such 
as  commas,  cross-hatching,  etc.,  for  a little  care  in 
working  will  enable  the  photographer  to  apply  the 
graphite  only  where  it  is  wanted,  the  important  point 
being  to  work  slowly  and  not  attempt  to  put  on  too 
much  at  once.  The  negative,  of  course,  should  be 

109 


MANIPULATION  OF  NEGATIVES 


supported  in  the  retouching  desk  while  work  is  being 

done  on  it,  and  should  be  examined  by  transmitted 

light,  proofs  being  taken  from  time  to  time  in  order  to 

see  how  the  work  is  progressing. 

Retouching  on  the  Back. — When  large  areas  are 

to  be  raised  in  value  or  when  the  lightening  is  to  be 

great,  it  is  best  to  apply  ground  glass  varnish  or  tracing 

paper  to  the  back  of  the  negative  and  work  on  this 

with  pencil  or  stump.  An  excellent  formula  for  ground 

glass  varnish  is  the  following: 

Gum  sandarac 90  grains 

Gum  mastic 20  grains 

Ether 2 ounces 

Dissolve  and  add 

Benzole 24  to  124  ounces 

The  quantity  of  benzole  added  determines  the  nature 
of  the  matt  obtained.  To  apply  this  the  negative  is  sup- 
ported in  the  left  hand  and  a small  pool  of  the  varnish 
is  poured  on  the  back,  which,  of  course,  should  be 
thoroughly  cleaned  and  should  be  free  from  dust.  The 
negative  is  then  tilted  so  that  the  varnish  runs  all  over 
the  plate,  the  excess  being  drained  back  into  the  bottle 
from  one  corner.  After  some  practice  it  will  be  possible 
to  flow  the  negative  neatly  without  getting  any  of  the 
varnish  on  the  film  side,  but  any  which  does  get  on  the 
film  may  readily  be  cleaned  off  by  means  of  a rag  wet 
with  alcohol  after  the  varnish  has  dried,  which  it  will 
do  in  a few  seconds,  and  should  the  pencil  work  not  be 
as  desired  alcohol  will  remove  the  ground  glass  varnish, 
and  the  negative  may  be  flowed  again. 

If  it  is  preferred  to  use  tracing  paper,  this  should  be 
selected  with  as  fine  a grain  as  possible  and  of  as  pure 
a white  as  can  be  obtained.  A line  about  1 /8-inch 
110 


RETOUCHING  ON  THE  RACK 


wide  of  LePage’s  or  Dennison’s  glue  or  of  Seccotine  is 
run  around  the  edges  of  the  negative  on  the  glass  side. 
The  tracing  paper,  which  should  be  cut  slightly  larger 
than  the  negative,  is  dampened  by  means  of  a sponge 
and  is  laid  on  the  negative,  being  pressed  down  so  as  to 
insure  firm  adhesion  of  the  glue.  The  negative  is  then 
set  aside  until  the  paper  is  dry,  when  the  latter  will  be 
found  to  be  stretched  taut  and  smooth.  Care  should 
be  taken  that  the  paper  is  not  dampened  too  much,  as 
if  this  is  done  it  will  expand  so  much  that  on  drying  it 
will  probably  split.  Work  may  be  done  to  almost  an 
unlimited  extent  on  this  paper  with  a pencil,  but  should 
it  be  found  that  the  paper  will  not  take  enough  graphite 
water  colors  may  be  used.  Evidently,  if  the  work 
proves  unsatisfactory  the  paper  may  easily  be  removed 
from  the  negative  and  be  replaced  by  fresh.  It  should 
be  noted  that  work  on  the  film  is  in  contact  with  the 
printing  paper,  so  must  be  done  with  greater  precision 
than  when  it  is  on  the  back,  as  in  the  latter  case  the 
pencil  lines  give  a diffused  image,  owing  to  their 
separation  from  the  sensitive  surface. 

If  it  is  desired  to  darken  an  area,  this  may  be  done 
either  by  working  on  the  film  with  a fine-pointed  pencil 
eraser,  which  should  be  rather  hard  instead  of  the  sort 
known  as  putty  rubber;  or  the  etching  knife  may  be 
used,  although  the  latter  is  not  recommended  unless 
it  is  desired  to  remove  entirely  a portion  of  the  film, 
since  it  is  difficult  to  do  only  a slight  amount  of  work 
in  this  manner.  A method  which  is  far  preferable  to 
using  the  etching  knife  is  to  incorporate  a slight  amount 
of  yellow  dye  with  the  ground  glass  varnish  (aurantia  is 
recommended)  and  to  scrape  away  the  varnish  from 

ill 


MANIPULATION  OF  NEGATIVES 


the  areas  to  be  darkened.  Obviously  this  method 
allows  of  doing  the  work  over  in  the  event  of  its  proving 
unsatisfactory  at  first,  which  is  not  the  case  if  the 
etching  knife  is  used.  A very  small  amount  of  dye  will 
give  a marked  effect. 

Combination  Printing. — It  sometimes  happens 
that  it  is  desired  to  combine  portions  of  two  or  more 
negatives,  as  in  printing  clouds  or  figures  into  a land- 
scape, and  there  are  several  ways  of  accomplishing  this. 

The  first  and  simplest  is  to  cut  a mask  the  size  and 
shape  of  the  portion  to  be  printed,  keeping  both  pieces 
of  the  black  paper;  namely,  the  portion  which  is  cut 
out  and  the  large  sheet  from  which  it  is  cut.  The  first 
negative  to  be  printed  from  is  placed  in  the  printing 
frame  with  the  paper  on  which  the  print  is  to  be  made 
and  the  portion  of  it  which  is  not  desired  is  shielded  by 
means  of  one  portion  of  the  mask.  When  printing  has 
gone  far  enough  the  paper  and  negative  are  removed 
from  the  frame  and  the  other  negative  is  placed  in  it, 
the  printing  paper  being  adjusted  in  register  with  the 
second  negative.  The  other  portion  of  the  mask  is  then 
used  to  shield  the  paper  from  light  and  the  second 
negative  is  printed  to  the  proper  depth.  Obviously 
this  method  is  applicable  only  to  printing-out  papers 
unless  special  means  are  employed  for  insuring  regis- 
tration, and  in  any  case  it  is  not  easy  to  manipulate 
the  masks  with  such  accuracy  as  to  show  no  outline 
at  the  junction. 

Another  method  for  securing  the  same  result  is  to 
make  a print  of  the  entire  first  negative,  then  to  make 
a print  of  the  second  and  to  cut  out  with  a sharp  knife 
from  this  print  those  portions  which  are  not  desired  in 

112 


COMBINATION  PRINTING 


the  completed  picture.  The  second  print  is  then  fast- 
ened in  the  proper  position  on  the  first  by  means  of  a 
few  touches  of  glue  and  the  whole  is  copied.  The 
negative  so  made  will  probably  show  the  outline  of  the 
second  print  on  the  first  and  this  should  be  retouched 
carefully.  If  the  scale  of  the  two  negatives  is  different 
one  or  the  other  must  of  course  be  enlarged  and  a 
portion  of  the  enlargement  (which  may  be  on  bromide 
paper)  must  be  used.  This  method  will  be  found 
simple  and  satisfactory. 

A third  method,  no  more  satisfactory  than  this  and  far 
more  complicated,  is  that  given  by  the  late  A.  Horsley 
Hinton  in  Photo  Miniature  No.  59,  but  a full  description 
would  require  more  space  than  can  be  given  here. 

There  are  numerous  opportunities  for  failure  in 
combination  printing,  but  careful  work  and  precise 
observation  will  enable  the  photographer  to  avoid  them. 
Care  must  of  course  be  taken  that  the  scale  is  the  same 
throughout;  that  is,  if  figures  are  printed  in  a landscape 
they  must  not  be  too  large  or  too  small  and  they  must 
have  the  proper  value  or  there  will  be  a discrepancy 
between  linear  and  atmospheric  perspective.  It  may 
seem  unnecessary  to  state  that  objects  printed  in  a 
landscape,  whether  clouds,  figures  or  trees,  should  be 
lighted  from  the  same  direction  as  the  landscape,  but 
the  writer  has  seen  prints  in  which  this  precaution  has 
not  been  taken,  the  effect  being  bizarre  in  the  extreme. 
Necessarily,  also,  the  quality  of  definition  should  be  the 
same  throughout.  It  may  seem  absurd  to  call  attention 
to  these  evident  facts,  but  it  is  necessary  that  the 
worker’s  observation  be  as  precise  and  accurate  as 
that  of  any  other  individual  who  will  be  likely  to  see 

8 113 


MANIPULATION  OF  NEGATIVES 

the  picture,  since  incongruities  of  any  sort  will  spoil 
the  psychic  effect  of  the  work.  Ordinary  care  would 
of  course  prevent  such  violations  of  unity  as  can  be  seen 
in  a picture  by  a welhknown  worker,  where  clouds  have 
been  printed  in  a marine,  the  work  having  been  done  with 
such  indifference  that  the  cloud  forms  have  been  printed 
directly  over  the  sails  of  a yacht  in  the  foreground. 

Combination  printing  is  not  easy  to  do,  but  the 
results  often  justify  the  labor  expended,  and  in  fact 
the  thorough  artist  will  not  consider  any  amount  of 
labor  excessive,  provided  it  affords  exactly  the  effect 
which  he  wishes  to  obtain,  it  being  far  better  to  spend 
six  months  in  the  production  of  one  satisfactory  picture 
than  to  make  a hundred  mediocre  ones  in  the  same 
time.  Michael  Angelo  is  credited  with  having  said  to  a 
person  who  remonstrated  with  him  for  giving  so  much 
attention  to  trifles:  “Trifles  make  up  perfection  and 

perfection  is  no  trifle.”  Whether  or  not  the  great 
Italian  ever  actually  said  this,  it  is  nevertheless  perfectly 
true,  and  although  the  writer  prefers  whenever  possible 
to  obtain  the  completed  picture  from  one  original 
negative,  it  cannot  be  too  strongly  impressed  on  the 
student  that  retouching,  combination  printing,  and 
modification  of  the  print  are  all  necessary  at  times,  and 
the  worker  should  not  permit  himself  to  be  influenced 
by  those  writers  or  advisers  who  maintain  that  such 
methods  are  not  legitimate  photography.  The  final 
result  is  the  only  thing  to  be  considered  and  the  worker’s 
attention  should  be  concentrated  on  securing  the 
pictorial  effect,  without,  however,  introducing  any 
violations  of  unity  resulting  from  an  evident  mixture 
of  mediums;  that  is,  photography  and  hand  work. 

114 


CHAPTER  VII 
ENLARGING 

Reasons  for  Enlarging. — Many  writers  say  that 
size  has  nothing  to  do  with  art  and  that  it  is  possible 
for  a small  picture  to  show  as  fine  artistic  quality — that 
is,  composition  of  line  and  mass  and  esthetic  feeling — as 
can  be  found  in  a large  one.  This  is  perfectly  true,  but 
the  fact  remains  that  pictorial  effect  depends  to  a great 
extent  on  the  size  of  the  picture,  and  that  the  larger 
the  print  the  more  likely  it  is  to  produce  the  desired 
effect  on  the  spectator.  This  is  probably  due  to  the 
circumstance  that  the  photographer  or  painter  who 
wishes  to  produce  a psychic  impression,  that  is,  to 
arouse  in  the  spectator  some  mood  or  emotion — which 
is  the  highest  function  of  art — is  necessarily  concerned 
very  largely  with  producing  an  illusion  of  reality,  the 
psychic  effect  being  more  likely  to  result  if  the  observer 
can  be  deceived  into  thinking  he  is  looking  at  the  actual 
objects  instead  of  merely  their  pictorial  representation. 
Since  natural  objects  are  usually  large  as  compared  to 
the  observer,  it  follows  that  a picture  of  a tree  or  a 
house  is  not  likely  to  produce  an  illusion  of  reality  when 
it  is  on  a small  scale,  for  the  observer  is  obliged,  in 
looking  at  the  real  tree  or  house,  to  move  his  eyes  in 
order  to  observe  the  entire  object,  whereas  this  does 
not  occur  with  a small  picture.  If,  however,  the  pic- 
ture be  18"X22"  or  20"X24"  it  will  be  necessary  for 
the  observer  to  move  his  eyes  in  order  to  see  the  entire 
picture  space,  and  this  motion  is  unconsciously  asso- 


ENLARGING 


ciated  with  the  idea  of  magnitude.  Hence  it  follows 
that  those  artists  who  are  concerned  merely  with 
esthetic  qualities  need  not  work  in  large  sizes,  but  the 
ones  whose  ambition  it  is  to  produce  a pictorial  effect 
should  make  their  prints  as  large  as  possible  without 
exceeding  the  natural  limitations  of  the  medium. 
Ordinarily  it  will  be  found  that  the  practical  limit  of 
size  is  about  20"X24",  but  it  is  also  true  that  a print 
11"X14"  has  much  greater  carrying  power  than  one 
8"X10",  the  smaller  being  essentially  portfolio  prints 
rather  than  wall  pictures. 

Reasons  for  Making  Enlarged  Negatives. — 
There  are  several  reasons  why  it  is  preferable  to  make 
an  enlarged  negative  and  a print  from  it,  rather  than 
to  enlarge  direct  on  bromide  paper,  the  most  important 
being  that  bromide  paper  cannot  be  considered  abso- 
lutely permanent,  but  scarcely  second  to  this  in  con- 
sequence is  the  fact  that  it  is  not  possible  to  get  so 
fine  a quality  in  the  lower  register  with  bromide  paper 
as  with  various  of  the  other  mediums.  Also,  the  pos- 
sibilities of  bromide  paper  are  limited  unless  the  worker 
resorts  to  various  toning  methods,  most  of  which  still 
further  diminish  the  stability  of  the  result.  Further, 
modification  of  relative  values  may  be  carried  out 
more  readily  on  a large  negative  than  on  a small  one, 
and  all  of  these  factors  operate  to  make  it  practically 
imperative  for  the  pictorial  worker  who  wishes  to 
produce  large  prints  to  make  enlarged  negatives  and 
contact  prints  in  one  or  another  of  the  better  mediums. 

Enlarging  Methods  and  Apparatus. — There  are 
almost  as  many  styles  of  enlarging  apparatus  as  there 
are  styles  of  camera,  the  simplest  being  the  fixed  focus 

116 


ENLARGING  METHODS 


enlarger,  which  consists  merely  of  a light-tight  box 
having  at  one  end  a space  for  holding  the  sensitive 
paper  or  plate  and  at  the  other  a space  for  holding  the 
negative  or  positive  to  be  enlarged  from,  with  a lens 
arranged  at  the  proper  point  inside  the  box  so  that  an 
enlarged  image  of  the  negative  or  positive  is  projected 
on  the  sensitive  surface.  This  instrument  is  limited  in 
its  application,  since  the  enlargement  always  bears  a 
definite  relation  to  the  original,  the  degree  of  enlarge- 
ment being  usually  two  diameters;  that  is,  4"X5"  is 
enlarged  to  8"X10"  or  is  enlarged  to 

^A"XSy2'\  These  instruments  are  very  cheap  and 
within  limitations  do  excellent  work,  but  far  preferable 
to  them  is  a more  flexible  piece  of  apparatus.  This 
may  be  either  a projection  lantern,  arranged  somewhat 
like  the  familiar  stereopticon,  or  it  may  be  a copying 
camera,  which  differs  from  the  fixed  focus  instrument 
in  having  an  extensible  bellows  so  that  any  degree  of 
enlargement  within  the  limits  of  the  instrument  may  be 
obtained,  and  is  usually  constructed  with  the  same 
mechanical  care  as  a good  camera.  The  copying  camera 
has  the  disadvantages  that  it  is  rather  expensive  and 
that  it  is  extremely  bulky  if  enlargements  greater  than 
11"X14"  are  desired,  whereas  the  projection  type  is 
relatively  cheap  and  compact  and  gives  enlargements  of 
practically  any  desired  size,  but  has  the  disadvantage 
that  it  must  be  used  in  the  dark  room,  since  the  sensi- 
tive substance  on  which  the  large  negative  is  to  be 
made  must  be  fastened  to  an  easel  instead  of  being 
contained  in  a plate  holder  as  is  the  case  with  the 
copying  camera.  Generally  speaking  the  writer  would 
prefer  a copying  camera  if  enlargements  not  over 


ENLARGING 


11"X14"  are  to  be  made,  and  for  sizes  greater  than 
this  the  projection  apparatus. 

Daylight  and  Artificial  Light. — Either  daylight 
or  artificial  light  may  be  used  for  illuminating  the 
original,  daylight  having  the  advantage  that  it  requires 
as  a rule  far  less  exposure  than  any  artificial  light, 
whereas  artificial  light  has  the  advantages  that  it  is 
more  uniform,  so  that  errors  in  exposure  are  less  likely 
to  occur,  and  that  its  use  makes  possible  working  at 
night.  If  daylight  is  employed  it  is  generally  necessary 
to  use  some  method  of  diffusing  it  so  that  shadows 
falling  on  the  window  will  not  be  reproduced  in  the 
enlargement,  and  this  may  be  accomplished  by  closing 
the  window  completely  with  an  opaque  shutter  except 
for  an  area  of  the  desired  size  and  in  this  opening  placing 
two  or  three  sheets  of  ground  glass  separated  from  each 
other  by  about  two  inches.  If  artificial  light  is  used  it 
will  be  necessary  either  to  diffuse  the  light  in  this 
manner  or  to  employ  between  the  source  of  illumina- 
tion and  the  negative  or  transparency  a pair  of  conden- 
sing lenses,  the  function  of  these  being  to  refract  all  the 
rays  falling  on  them  from  the  illuminant  into  a cone  of 
light  the  apex  of  which  is  approximately  at  the  dia- 
phragm of  the  projection  lens.  It  will  be  apparent 
that  the  use  of  condensers  diminishes  the  necessary  ex- 
posure and  the  projection  type  of  apparatus  is  generally 
supplied  with  this  adjunct.  Figure  40  shows  arrange- 
ments of  three  forms  of  enlarger,  (A)  representing 
diagrammatically  the  copying  camera  when  used  with 
daylight,  (B)  the  projection  apparatus  with  the  same 
form  of  illumination,  and  (C)  the  projection  apparatus 
with  artificial  light.  Various  forms  of  artificial  light 

118 


DAYLIGHT  AND  ARTIFICIAL  LIGHT 


may  be  used  satisfactorily,  among  them  being  the 
incandescent  gas  burner,  the  incandescent  electric  light, 
acetylene  gas,  and  the  Cooper-Hewitt  mercury  vapor 
arc.  The  electric  arc  is  not  generally  recommended, 
since  it  is  somewhat  inconvenient  to  operate.  It  should 
be  observed  that  if  condensing  lenses  are  used  the 


Fig.  40. 


source  of  illumination  and  the  axis  of  the  projection 
lens  should  be  accurately  in  line  with  the  axis  of  the 
condenser  or  uneven  illumination  at  the  easel  may 
result,  which  will  also  be  the  case  should  the  projection 
lens  and  the  source  of  illumination  not  be  approximately 
at  the  conjugate  foci  of  the  condensing  system.  There- 
fore some  means  should  be  provided  whereby  the 
illuminant  may  be  moved  nearer  to  or  farther  from  the 
condensers,  so  that  a uniform  screen  may  be  obtained 

119 


ENLARGING 


whether  the  projection  lens  is  racked  forward  or  back 
as  may  be  necessary  for  different  degrees  of  enlarge- 
ment. 

It  is  possible  to  obtain  an  arrangement  known  as  an 
“enlarging  back,”  this  being  a device  which  carries 
the  small  negative  or  transparency  and  several  sheets 
of  ground  glass  for  diffusing,  the  whole  being  capable 
of  attachment  to  a shutter,  and  fitting  the  back  of  a 
view  camera.  This  device  is  strongly  recommended 
to  anyone  who  possesses  a view  camera  and  wishes  to 
work  by  daylight  or  mercury  vapor  arc,  since  it  fur- 
nishes a relatively  cheap  and  thoroughly  satisfactory 
means  for  enlarging. 

Glass  or  Paper  Negatives. — Either  dry  plates  or 
bromide  paper  may  be  used  for  the  enlarged  negatives, 
the  writer  generally  preferring  the  latter  for  the  following 
reasons : 

1.  It  is  cheaper. 

2.  It  is  lighter  and  more  compact  for  storage. 

3.  It  is  easier  to  manipulate  in  the  dark  room. 

4.  Modification  of  relative  values  may  be  made  di- 
rectly on  the  paper  with  pencil  or  stump  without  the 
need  of  retouching  medium  or  ground  glass  substitute. 

5.  It  is  impossible  to  over-develop  a negative  on 
bromide  paper,  since  development  proceeds  as  far  as 
the  exposure  demands  and  then  ceases,  there  being 
observable  a definite  point  at  which  development  stops, 
so  that  one  possible  source  of  failure  is  thus  avoided. 

The  advantages  of  dry  plates  are: 

1 . Printing  is  slightly  more  rapid  for  a given 
quality  of  negative.  This,  however,  is  not  of  great  im- 
portance, as  may  be  understood  from  the  fact  that 


TECHNIQUE  OF  ENLARGING 


many  of  the  writer’s  paper  negatives  print  on  platinum 
in  three  or  four  minutes  with  bright  sunlight,  and  it 
often  happens  that  a glass  negative  will  require  more 
time.  Generally  speaking  the  increased  printing  time  of 
paper  negatives  over  that  of  glass  is  of  no  importance, 
especially  to  the  pictorial  worker, who  does  not,  as  a rule, 
wish  to  make  more  than  a few  prints  in  a day. 

2.  Dry  plates  are  capable  of  giving  finer  detail 
than  bromide  paper,  since  the  grain  of  the  paper  stock 
tends  to  break  up  fine  lines.  This,  however,  may  be  a 
disadvantage,  as  the  pictorialist  generally  desires  breadth 
rather  than  minute  definition. 

3.  It  is  a little  easier  to  manipulate  glass  negatives 
in  printing,  but  the  difference  is  so  slight  as  to  be  hardly 
worth  noticing. 

4.  Should  the  quality  of  the  transparency  not  be 
as  desired  it  is  easier  to  correct  the  fault  by  shortening 
or  prolonging  the  development  of  the  large  negative 
than  is  the  case  with  bromide  paper. 

Some  workers  use  Eastman  Portrait  Film  for  en- 
larged negatives,  and  this  is  very  good,  the  chief  dis- 
advantage being  the  extreme  rapidity  of  the  emulsion, 
which  makes  it  difficult  to  secure  correct  exposure,  and 
the  fact  that  the  larger  sizes,  if  printed  in  sunlight,  tend 
to  buckle  in  the  printing-frame,  giving  streaked  prints. 

Technique  of  Enlarging. — Obviously  if  an  en- 
larged negative  is  to  be  made  it  must  be  made  from  a 
transparency  instead  of  from  a small  negative,  and  the 
quality  of  the  transparency  is  of  prime  importance. 
The  contrast  in  the  transparency  must  be  adjusted  to 
the  medium  to  be  used  for  the  large  negative,  and 
although  no  definite  rules  can  be  given  for  securing  the 
desired  contrast,  since  this  varies  according  to  cir- 

121 


ENLARGING 


cumstances,  nevertheless  some  general  indications  may 
be  given.  A fast-working  plate  will  require  a stronger 
transparency  than  a slow  one,  the  same  being  true  of 
bromide  papers,  since  slow  emulsions  tend  naturally 
to  give  more  contrast  than  rapid  ones.  Also,  the  stronger 
the  light  used  for  projection  the  stronger  the  trans- 
parency must  be,  since  a powerful  illuminant  tends 
to  give  softer  results  than  a weaker  one.  The  writer’s 
own  practice  is  somewhat  as  follows.  The  light  used 
for  projection  is  a powerful  500  watt  tungsten  incan- 
descent with  condensers  and  a fast-working  bromide 
paper  is  generally  employed  for  the  negative.  The 
transparency  is  made  on  a Standard  Orthonon  or  Seed’s 
L.  Ortho  Non -Halation  plate,  this  being  placed  in  con- 
tact in  a printing  frame  with  the  original,  which  is 
usually  rather  soft.  An  exposure  of  about  one  second 
is  given  at  a distance  of  four  feet  from  an  incandescent 
gas  burner  and  the  transparency  is  developed  in  a soft 
working  developer  until  it  has  a slight  tone  in  the  lights 
and  an  ordinary  newspaper  may  be  read  through  the 
densest  portion  when  the  transparency  is  laid  directly 
in  contact  with  the  paper,  this  determination  of  course 
being  made  after  the  transparency  has  been  fixed, 
washed  and  dried.  It  will  be  seen  from  this  that  the 
transparency  is  distinctly  thin  in  the  shadows  and  has  a 
slight  veil  in  the  lights,  no  part  being  clear  glass.  The 
resultant  negative  is  decidedly  soft  in  quality,  and 
will  give  in  platinum  a print  having  tone  in  the  lights 
and  medium  or  dark  gray  shadows.  Of  course,  this 
technique  is  varied  when  a different  result  is  desired, 
but  it  will  always  be  found  that  a double-coated  plate  is 
desirable  for  the  transparency,  since  a single-coated 


TECHNIQUE  OF  ENLARGING 


plate  is  very  apt  to  show  halation  when  used  in  these 
circumstances.  For  making  the  large  negative  the 
writer  generally  prefers  a fast  bromide  paper,  choosing 
of  course  one  in  which  the  emulsion  is  coated  on  a thin 
stock,  in  order  that  printing  may  be  as  rapid  as  possible. 
If,  however,  a plate  is  to  be  employed,  the  one  chosen  is 
of  the  comparatively  slow  non-halation  variety,  since 
this  approximates  very  closely  to  the  working  quality  of 
the  paper  mentioned.  The  paper  is  in  itself  halation 
proof,  as  has  been  stated  in  Chapter  III.  With  the 
illuminant  and  transparency  indicated  the  exposure 
for  enlarged  negatives  will  generally  be  about  15  or  20 
seconds,  and  the  paper  or  plate  is  developed  in  a fairly 
strong  solution,  generally  the  metol-hydroquinone  de- 
veloper given  in  Chapter  IV,  taking  one  ounce  of  stock 
solution  to  15  ounces  of  water.  Development  will  be 
complete  in  two  or  three  minutes  and  the  negative  is 
then  fixed  in  an  acid  hypo  bath  and  washed  for  half  an 
hour  in  running  water.  If  several  large  paper  negatives 
are  made  and  washed  together  care  should  be  taken 
that  the  flow  of  water  into  the  tray  is  such  as  to  keep 
the  negatives  separated  or  they  will  not  wash  thoroughly 
and  stains  may  appear  at  a later  date.  It  will  be  found 
that  some  bromide  papers  show  a decided  tendency  to 
curl  when  dried,  and  if  this  is  inconvenient  it  may  be 
prevented  by  soaking  the  negative  immediately  after 
washing  in 

Water 15  ounces 

Glycerine 1 ounce 

and  hanging  up  to  dry.  As  indicated  above,  paper 
negatives  may  be  modified  directly  with  pencil  or 

123 


ENLARGING 

stump  as  desired,  and  either  paper  or  glass  negative 
may  be  intensified  or  reduced  either  locally  or  generally 
by  the  methods  given  in  Chapter  VI. 

Sometimes  the  transparency  is  made  by  the  carbon 
process,  using  either  the  special  transparency  tissue  or 
the  Ivory  Black,  and  printing  from  two  to  ten  times 
as  long  as  would  be  done  for  a print  on  paper.  The 
tissue  is  transferred  to  ground  glass,  no  special  prepara- 
tion of  the  latter  being  necessary,  since  the  roughness 
of  the  glass  will  cause  the  tissue  to  adhere  perfectly. 
The  ground  glass  will  cause  some  diffusion  in  the 
enlargement,  and  if  this  is  not  desired  the  transparency 
may  be  flowed  with  Lumiere’s  autochrome  varnish, 
which  will  do  away  with  the  granular  effect. 

Some  workers  advocate  making  a large  trans- 
parency by  projection  and  making  the  negative  from 
this  by  contact  printing,  but  the  writer  does  not  feel 
that  any  better  quality  results  from  this  method,  which 
has  the  disadvantage  of  being  decidedly  more  expen- 
sive. If  it  is  desired  to  adopt  this  method,  it  is  advised 
that  the  large  negative  be  made  by  the  carbon  process, 
using  Ivory  Black  tissue,  printing  about  ten  times  as 
long  as  for  a paper  print,  and  transferring  to  ground 
glass,  since  this  reproduces  the  gradations  of  the  posi- 
tive automatically,  and  there  is  less  opportunity  for 
failure  through  incorrect  development. 

Bromide  Enlarging. — If  the  worker  does  not  wish 
to  make  enlarged  negatives  and  is  willing  to  accept  the 
limitations  of  bromide  paper  he  may  make  enlargements 
direct  in  that  medium,  the  process  being  the  same  as  in 
making  enlarged  negatives,  except  that  the  enlargement 
is  made  from  the  original  negative  instead  of  from  a 


BROMIDE  ENLARGING 

transparency.  The  limitations  in  question  are:  (1) 

impermanence  unless  redeveloped  to  a brown  color; 
(2)  the  impossibility  of  securing  as  rich  blacks  as  are 
obtainable  with  other  mediums;  (3)  the  surface  texture 
of  bromide  paper  is  not  so  pleasing  as  that  of  some 
other  papers. 

Bromide  paper  may  be  obtained  in  many  different 
grades  and  surfaces,  from  glossy  to  dull,  in  many  differ- 
ent degrees  of  contrast,  and  in  many  textures,  from 
smooth  to  very  rough.  It  is  possible  to  obtain  bromide 
papers  the  surface  of  which  approximates  closely  to 
that  of  platinum  paper,  and  there  is  one  in  which  the 
emulsion  is  coated  on  a Japanese  tissue,  this  paper 
being  capable  of  giving  very  beautiful  results.  Bromide 
paper  is  also  furnished  in  a variety  of  weights,  and  in 
white  or  buff  stock,  the  latter  being  especially  suitable 
for  sunlight  effects  and  for  portraiture,  particularly 
when  redeveloped  to  give  a brown  image. 

In  bromide  enlarging  one  of  the  most  important 
points  is  to  have  the  strength  of  the  negative  adjusted 
to  the  paper  in  use,  since  it  is  not  easy  to  introduce 
variations  in  contrast  by  varying  the  treatment  of  the 
paper.  If  the  negative  is  too  strong  a soft  print  may 
be  obtained  by  over-exposing  and  developing  in  a very 
dilute  solution,  arresting  development  before  complete, 
that  is,  when  the  appearance  of  the  print  is  satisfactory; 
but  this  is  not  easy  to  do,  and  if  the  print  is  to  be  rede- 
veloped such  treatment  will  certainly  result  in  a poor 
color.  If  the  negative  is  too  weak  it  should  be  intensi- 
fied, for,  although  a bromide  print  may  be  intensified 
in  the  same  manner  as  a negative,  this  tends  to  diminish 
the  stability  of  the  image.  If  rich  prints  are  to  be 

125 


ENLARGING 


obtained  the  negative  should  be  of  such  quality  that 
normal  treatment  will  just  give  the  desired  quality  in 
the  lights  and  at  the  same  time  will  give  the  darkest 
shadows  which  the  paper  is  capable  of  rendering.  In 
other  words,  it  should  exhaust  the  scale  of  the  paper, 
for  bromide  paper  is  not  a long  scale  process,  and  does 
not,  normally,  give  as  strong  shadows  as  platinum  or 
carbon.  If  the  print  is  to  be  redeveloped,  however, 
the  negative  should  not  be  too  strong,  for  the  shadows 
must  not  be  blocked  up,  any  suggestion  of  reversal — 
from  over-exposure — giving  a poor  color. 

Practically  any  developer  may  be  used,  though  it 
is  advised  to  employ  that  recommended  by  the  manu- 
facturer of  the  paper  in  use,  and  it  may  be  noted  that  a 
strong  amidol  developer  tends  to  give  a cold  black. 
Pyro  is  not  generally  recommended,  on  account  of  its 
staining  tendency,  though  if  carefully  used  it  may  be 
made  to  give  a very  pleasing  warm  color.  Generally 
speaking,  the  developer  should  be  used  rather  strong, 
especially  if  the  print  is  to  be  redeveloped.  An  acid 
fixing  bath  with  hardener  is  advised,  particularly  if  the 
print  is  to  be  redeveloped,  since  this  operation  tends 
to  cause  blisters.  Washing  should  be  thorough,  for 
on  the  removal  of  the  products  of  fixation  depends  the 
stability  of  the  print,  and  it  is  imperative  that  all  the 
hypo  be  removed  from  the  emulsion  of  a print  intended 
for  redevelopment,  since  any  hypo  remaining  in  the 
film  will  combine  with  the  potassium  ferricyanide  in 
the  bleacher,  forming  Farmer’s  reducer,  which  will  dis- 
solve out  portions  of  the  silver  image,  spoiling  the 
print.  The  fixing  bath  should  be  renewed  at  frequent 
intervals,  for  it  will  apparently  work  satisfactorily  after 

126 


BROMIDE  ENLARGING 


it  has  actually  ceased  to  do  so,  and  an  exhausted  fixing 
bath  is  prejudicial  to  the  stability  of  the  print. 

A bromide  print  will  not  over-develop,  the  develop- 
ment proceeding  as  far  as  the  light-action  calls  for  and 
then  stopping,  development  usually  requiring  from  two 
to  three  minutes — depending  on  the  paper  and  the 
developer — and  if  the  print  is  to  remain  black  and 
white  it  is  sufficient  to  develop  until  the  desired  depth 
has  been  reached — allowing  for  the  facts  that  the  print 
will  look  darker  when  dry  than  when  wet  and  that  it 
looks  darker  in  the  dark-room  than  it  will  in  full  light — 
and  then  fix,  but  if  the  print  is  to  be  redeveloped  it  is 
necessary  to  insure  that  all  the  light-affected  silver  has 
been  reduced  to  the  metallic  state  (which  cannot  be 
determined  by  inspection)  and  this  is  accomplished  by 
continuing  development  for  as  much  longer  as  is 
required  for  the  print  to  assume  the  proper  appearance. 
That  is,  if  development  is  complete  and  has  stopped  in 
two  minutes,  the  print  should  be  developed  for  a total 
of  four  minutes.  Longer  development  will  do  no  harm 
unless  the  dark-room  light  is  so  strong  as  to  cause  fog. 
A print  intended  for  redevelopment  should  be  a trifle 
darker  in  its  original  state  than  it  is  to  be  when  finished. 

If  the  normal  black  image  is  not  satisfactory,  the 
print  may  be  given  a warmer  color  by  toning,  and  there 
are  many  formulae  for  this  purpose,  the  production  of 
brown,  blue,  green  or  red  tones  being  possible,  some 
workers  having  even  produced  prints  in  variegated 
colors.  However,  any  toning  method  except  that  which 
depends  on  the  conversion  of  the  image  into  silver 
sulphide,  giving  a brown  color,  tends  to  diminish  the 
stability  of  the  print,  sulphiding,  on  the  other  hand, 

127 


ENLARGING 


increasing  this  stability.  Sulphiding  may  be  accom- 
plished by  the  hypo-alum  toning  method,  but  a quicker, 
more  convenient,  and  equally  good  process  is  as  follows : 
After  fixing  and  washing — and  drying,  if  desired — the 
print  is  immersed  in 


Water 10  ounces 

Potassium  ferricyanide 40  grains 

Potassium  bromide 60  grains 


This  should  be  made  up  fresh  for  use,  the  strength  not 
being  important,  as  the  only  effect  of  using  the  bleacher 
more  dilute  is  to  make  it  act  more  slowly.  In  this 
solution  the  print  will  bleach,  and  the  action  should  be 
continued  until  all  the  black  of  the  image  has  disap- 
peared, though  a residual  brownish  image  will  remain. 
The  print  is  then  rinsed  several  times  to  free  it  from 
the  bleacher  and  is  immersed  in 

Water 10  ounces 

Barium  sulphide 120  grains 

This  will  not  form  a perfect  solution,  but  may  never- 
theless be  used.  The  print  will  redevelop  in  this 
solution,  assuming  a warm  brown  color,  and  should 
be  allowed  to  remain  until  all  the  original  detail  has 
returned,  when  it  is  washed  for  a few  minutes,  swabbed 
with  a tuft  of  cotton,  and  put  to  dry.  Barium  sulphide 
is  preferable  to  the  generally  recommended  sodium 
sulphide,  both  because  it  tends  to  give  a cooler  brown 
and  because  it  keeps  better  than  the  sodium  salt,  a 
partly  decomposed  sample  of  sodium  sulphide  giving 
a poor  color.  The  solution  should,  however,  be  made 
up  fresh  for  use.  If  the  color  given  by  this  method  is 
too  warm,  a cooler  effect  may  be  secured  by  using  the 
128 


CAPRI 

BY  KARL  STRUSS 
Prom  a Bromide  Enlargement 


BROMIDE  ENLARGING 

bleacher  very  dilute  and  arresting  bleaching  when  only 
partially  completed,  by  rinsing  the  print  quickly  in 
water,  the  subsequent  operations  being  the  same  as  in 
the  other  case.  If  this  is  done  the  final  image  will 
consist  partly  of  black  metallic  silver  and  partly  of 
brown  silver  sulphide,  the  exact  color  depending  on 
the  extent  of  the  bleaching.  Some  workers  find  it 
difficult  to  secure  uniform  bleaching  when  using  this 
method,  but  if  the  print  is  dried  before  bleaching  there 
should  be  no  trouble.  An  alternative  method  is  to 
bleach  fully,  to  redevelop  partly  in  a very  dilute  non- 
staining developer,  and  to  complete  redevelopment  in 
the  barium  sulphide  solution,  the  final  image  in  this 
case  also  consisting  partly  of  metallic  silver  and  partly 
of  silver  sulphide. 

Whether  the  prints  are  black  or  brown  the  richness 
of  the  shadows  and  the  brilliance  of  the  lights  are 
greatly  increased  by  varnishing.  If  it  is  desired  to 
varnish  without  changing  the  color  of  the  print  French 
picture  varnish  diluted  with  alcohol  may  be  used,  the 
print  being  dipped  into  this  and  hung  up  to  dry.  If  a 
slight  yellowing  of  the  print  is  not  objectionable 
Johnson’s  or  Old  English  floor  wax  may  be  used,  being 
applied  with  a brush  or  rag  and  polished  with  a moder- 
ately stiff  brush,  the  final  polish  being  given  with  a 
soft  cloth.  This  improves  the  appearance  of  a strong 
print  to  a marked  degree. 


9 


PART  III 

PRINTING  METHODS 


CHAPTER  VIII 

THE  IDEAL  MEDIUM 

No  printing  medium  possesses  all  the  characteristics 
which  are  desirable,  and  the  selection  of  the  medium  in 
which  the  negative  is  to  be  rendered  must  therefore 
depend  on  the  particular  qualities  that  are  to  be  secured 
in  the  completed  picture.  Thus,  some  mediums  will 
render  the  lighter  gradations  satisfactorily  but  fail  to 
give  good  quality  in  the  lower  register,  whereas  others 
are  satisfactory  in  shadow  rendering  but  fail  to  give 
good  quality  in  the  lights.  Also,  some  mediums  which 
render  gradations  nicely  do  not  possess  a pleasing  sur- 
face texture,  while  others  which  have  a good  texture 
fail  in  the  rendering  of  the  tones  of  the  negative.  The 
present  chapter  will  give  so  far  as  possible  a discussion 
of  the  characteristics  which  the  ideal  medium  should 
possess,  and  in  the  next  chapter  the  different  mediums 
will  be  considered  with  reference  to  the  advantages  and 
disadvantages  of  each. 

Permanence. — If  pictures  are  made  for  sale  neces- 
sarily honesty  demands  that  they  should  not  be  likely 
to  deteriorate  in  the  course  of  time  as  the  result  of 
exposure  to  light  and  air.  All  of  the  mediums  considered 
in  this  book  possess  this  characteristic  except  that  the 
pigment  mediums  may  be  fugitive  if  improper  pigments 
are  used  and  that  a black  and  white  bromide  print  can- 
not be  considered  absolutely  stable.  If,  however,  the 
proper  colors  are  selected  these  mediums  may  be  as  stable 
as  an  oil  painting  or  a charcoal  sketch,  and  it  is  known 

133 


THE  IDEAL  MEDIUM 


that  charcoal  drawings  are  in  existence  to-day  which 
were  made  at  least  20,000  years  ago.  Of  course,  no 
picture  is  necessarily  permanent,  since  any  may  be  de- 
stroyed, but  some  mediums  are  so  unstable  that  the 
image  will  partially  disappear  in  the  course  of  com- 
paratively few  years,  even  if  carefully  treated. 

Rendering  of  Gradations. — The  printing  medium 
should  be  capable  of  rendering  with  absolute  fidelity  all 
of  the  gradations  of  the  negative  from  pure  white  to 
pure  black.  Since  these  gradations  may  proceed  by 
imperceptible  transitions  it  necessarily  follows  that  the 
paper  must  be  highly  sensitive  to  slight  variations  of 
light  action,  although  it  is  of  course  possible  to  make  a 
negative  in  which  the  scale  of  gradation  exceeds  the 
power  of  any  printing  paper  to  render,  this  being  due 
to  the  fact  that  the  negative  is  examined  by  transmitted 
light,  whereas  the  print  is  examined  by  reflected  light, 
and  the  paper  support  on  which  the  image  rests  absorbs 
a considerable  proportion  of  the  incident  light. 

Texture. — Although  the  superficial  texture  of  the 
print  has  nothing  to  do  with  the  pictorial  effect,  which 
depends  solely,  so  far  as  the  print  is  concerned,  on  the 
rendering  of  the  gradations  of  the  negative,  neverthe- 
less this  matter  of  texture  is  of  considerable  importance, 
the  esthetic  value  of  the  picture  depending  on  it  to  a 
great  extent.  That  is,  if  the  surface  of  the  print  is  of  a 
quality  which  is  inherently  unpleasant  to  the  eye,  the 
observer  will  unconsciously  be  repelled  by  it,  this 
feeling  of  displeasure  being  at  times  so  great  as  to 
impair  seriously  the  psychic  effect  of  the  picture.  It  is 
generally  accepted  that  a dull  surface  is  more  pleasant 
to  the  eye  than  a glossy  one,  though  for  some  effects  a 

134 


MODIFICATIONS  OF  VALUES 


lustre  may  be  preferred,  and  it  is  also  usually  the  case 
that  a slight  roughness  is  more  agreeable  than  a smooth 
surface,  especially  if  the  roughness  is  irregular  in 
character. 

Modifications  of  Color. — Photography  is  essen- 
tially a monochromatic  art,  although  at  times  variations 
of  color  are  introduced.  Still,  the  color  chosen  for  a 
picture  may  be  of  great  importance  as  regards  the 
pictorial  effect,  as  will  be  realized  if  we  consider  the 
result  of  printing  a snow  scene  in  brown.  The  prevail- 
ing tone  of  a summer  or  autumn  landscape  is  generally 
warm;  that  is,  tending  toward  yellow  or  red  rather 
than  toward  blue,  and  that  of  a spring  or  winter  land- 
scape is  generally  cold.  If  an  unsuitable  color  is  used 
for  printing,  it  will  be  difficult  to  produce  the  desired 
illusion  of  reality,  and  the  printing  medium  should 
therefore  be  flexible  in  this  respect,  though  it  is  generally 
desirable  to  avoid  the  more  pronounced  colors,  such  as 
blue,  green,  and  red,  and  to  confine  oneself  to  cold, 
neutral,  and  warm  black  and  to  various  shades  of 
brown.  If  the  worker’s  aim  is  merely  to  produce  an 
esthetically  pleasing  result  and  no  value  is  attached  to 
the  illusion  of  reality,  a neutral  black  will  generally  be 
found  most  satisfactory. 

Modifications  of  Relative  Values. — It  should 
be  possible  within  limits  to  modify  relative  values  in 
the  print,  since  it  is  often  inconvenient  to  make  in  the 
negative  the  changes  necessary  to  pictorial  effect.  This, 
however,  is  not  of  great  importance,  for  such  changes 
can  always  be  produced  in  the  negative  if  the  worker 
will  give  the  necessary  time  and  effort,  and  the  power  of 
modifying  values  in  the  print  may  sometimes  constitute 

135 


THE  IDEAL  MEDIUM 


a positive  disadvantage,  the  worker  being  apt  to  be  led 
astray  by  this  ability  and  to  do  more  than  should 
properly  be  done. 

Modifications  of  Total  Contrast. — It  is  import- 
ant that  the  printing  medium  should  be  readily  con- 
trolled as  regards  total  contrast;  that  is,  difference 
between  the  extremes  of  light  and  dark,  since  it  is  often 
inconvenient  and  sometimes  impossible  to  intensify  or 
reduce  the  negative  in  the  desired  manner.  Of  course 
if  one  were  always  sure  of  producing  the  proper  quality 
of  negative  and  were  always  sure  of  making  the  final 
print  in  the  medium  chosen,  this  flexibility  in  the  print- 
ing medium  would  be  of  no  importance,  but  it  is 
obviously  impossible  to  be  certain  of  always  obtaining 
the  proper  degree  of  contrast  in  the  negative  and  it  not 
infrequently  happens  that  the  photographer  will  ul- 
timately decide  on  a different  printing  medium  than 
the  one  originally  selected,  so  that  the  ability  to  control 
the  contrast  in  the  print  is  of  no  slight  consequence. 
It  is  true  that  greater  contrast  may  be  secured  by  print- 
ing slowly,  whatever  the  medium  may  be;  that  is,  a 
print  made  in  the  shade  will  always  show  more  contrast 
than  one  made  on  the  same  paper  from  the  same  nega- 
tive if  printed  in  direct  sunlight,  but  practically  this 
method  of  variation  is  limited  in  its  application.  The 
writer  has  known  of  a satisfactory  print  being  got  from 
an  exceedingly  soft  negative  by  printing  far  away  from 
a window,  the  actual  printing  time  being  forty-eight 
hours,  whereas  printed  in  direct  sunlight  the  negative 
in  question  would  have  required  not  over  twenty 
seconds,  but  it  is  seldom  convenient  to  make  use  of 
any  such  prolonged  exposure  as  this  and  the  ideal 

136 


DUPLICATION 


medium  would  permit  of  the  desired  result  being 
obtained  more  readily. 

Convenience. — Convenience  and  rapidity  of  ma- 
nipulation are  not  so  important  to  the  pictorial  worker 
as  to  the  commercial  photographer,  since  the  former 
does  not  usually  wish  to  turn  out  prints  in  quantity, 
being  more  concerned  with  the  production  of  a few 
pictures  of  high  quality.  Other  things  being  equal, 
however,  the  more  convenient  method  is  to  be  pre- 
ferred and  it  is  regrettable  that  the  finest  printing 
mediums  (with  the  exception  of  bromoil)  require  either 
daylight  or  else  a very  powerful  artificial  light  such  as 
the  mercury  vapor  arc,  many  amateurs  who  do  exceed- 
ingly fine  work  being  so  situated  that  their  daylight 
hours  for  working  are  limited  to  Sundays  and  holidays. 

Duplication. — One  of  the  advantages  of  photo- 
graphy over  most  mediums  of  expression  is  the  faculty 
of  duplication,  whereby  any  number  of  identical  or 
closely  similar  prints  may  be  made  from  a satisfactory 
negative,  and,  though  this  power  is  of  more  value  to 
the  commercial  than  to  the  pictorial  worker,  never- 
theless it  is  by  no  means  to  be  ignored  by  the  latter, 
and  it  is  to  be  regretted  that  with  the  finer  pictorial 
mediums  duplication  is  not  easy  unless  the  prints  are 
made  at  the  same  time.  If  extensive  local  work  has 
been  done  in  gum  or  oil,  it  may  be  impossible  to  repeat 
a success. 


CHAPTER  IX 

DISCUSSION  OF  VARIOUS  MEDIUMS 

The  following  chapter  will  give  a discussion  of  the 
advantages  and  disadvantages  inherent  in  the  more 
desirable  pictorial  mediums,  namely,  platinum  (com- 
mercial and  hand-sensitized),  carbon  (single  and  mul- 
tiple), gum,  gum-platinum,  oil  and  bromoil  (including 
transfer),  and  photogravure. 

Platinum,  Commercial.— A dv  an  tag  es. — 1.  The 
manipulation  of  platinum  is  simpler  and  more  rapid 
than  that  of  any  of  the  other  pictorial  mediums. 

2.  Platinum  renders  gradations  in  the  lights  better 
than  does  any  other  medium  and  in  the  half-tones  and 
shadows  as  well  as  most  of  the  others. 

3.  Modifications  of  color  ranging  through  cold  and 
neutral  black,  warm  black,  brown  and  sepia  are  readily 
obtained. 

4.  Modifications  of  contrast  are  very  easily  made, 
platinum  being  more  flexible  in  this  respect  than  most 
other  mediums. 

5.  The  superficial  texture  is  generally  pleasing, 
since  the  image  consists  of  a deposit  of  fine  particles  of 
metallic  platinum  on  the  paper  stock,  no  gelatine  emul- 
sion being  used,  for  which  reason  the  surface  is  lustreless. 

6.  Duplication  of  results  is  comparatively  easy. 

Disadvantages. — 1.  Commercial  platinum  is  obtain- 
able in  only  a few  different  textures,  these  being  usually 
limited  to  smooth  and  slightly  rough. 

2.  Modifications  of  relative  values  are  not  easily 


CARBON 


made,  it  being  in  fact  almost  impossible  to  attain  this 
result  except  by  the  laborious  and  rather  unsatisfactory 
process  of  brush  development  with  glycerine. 

3.  Commercial  platinum  paper  will  not  render 
shadow  gradations  as  well  as  some  other  mediums,  nor 
does  it  give  so  rich  a black  as  can  be  obtained  with 
other  processes. 

Platinum,  Hand  -Sensitized  . — H and-sensitized 
platinum  presents  practically  all  the  advantages  of 
commercial  platinum  with  the  addition  of  improved 
rendering  of  shadows  (through  multiple  printing)  and 
the  possibility  of  using  a paper  support  of  any  desired 
texture  or  color.  The  only  disadvantages  which  it 
possesses  as  compared  with  commercial  platinum  are 
that  it  is  somewhat  more  laborious  to  prepare  the 
paper  than  to  buy  it  ready  prepared  (the  sensitizing  is, 
however,  by  no  means  difficult  and  requires  practically 
no  experience),  that  it  is  somewhat  more  expensive  to 
prepare  one’s  own  paper  than  to  buy  the  commercial 
variety,  and  that  duplication  is  not  so  easy. 

Carbon. — Advantages. — 1.  Carbon  renders  shadow 
gradations  as  well  as  any  other  printing  medium  and 
better  than  most. 

2.  Anyone  of  about  forty  different  colors  maybe  used. 

3.  It  is  fairly  easy  to  make  modifications  of  relative 
values  in  the  print. 

4.  It  is  easy  to  make  modifications  of  total  contrast 
by  multiple  printing. 

5.  By  multiple  printing  in  different  colors  some 
very  beautiful  effects  are  obtained  which  are  quite 
beyond  the  power  of  most  other  mediums  to  secure; 
thus  for  portrait  work  if  a rather  strong  print  in  red 

139 


DISCUSSION  OF  VARIOUS  MEDIUMS 


chalk  be  put  on  a yellow  paper  and  over  this  a com- 
paratively light  print  in  ivory  black  the  result  will  be 
that  the  extreme  lights  will  have  a yellow  tone,  ranging 
through  orange,  red,  and  warm  black  to  neutral  black, 
this  being  a very  desirable  quality  of  print  for  portraiture. 

6.  Any  color  and  practically  any  texture  of  paper 
support  may  be  used. 

7.  A good  carbon  print,  especially  a multiple  print, 
has  a richness  in  the  shadows  which  approximates  that 
of  an  oil  painting,  this  being  due  to  the  fact  that  the  emul- 
sion has  appreciable  thickness,  so  that  the  observer  has 
the  sense  of  looking  through  a layer  of  pigment  instead  of 
merely  at  it,  as  is  the  case  with  most  printing  mediums. 

8.  Duplication  of  results  is  comparatively  easy. 

Disadvantages . — 1.  It  is  not  very  easy  to  modify 

total  contrast  in  single  printing. 

2.  The  process  is  somewhat  laborious  to  handle. 

3.  It  is  almost  impossible,  except  in  the  case  of 
prints  in  a very  high  key,  to  secure  a lustreless  surface. 

4.  The  process  is  difficult  to  handle  in  hot  weather. 

5.  Pure  high-lights  are  not  easily  obtained  except 
by  means  of  hand- work  on  the  print. 

Gum. — Advantages. — 1.  The  choice  of  color  and 
texture  of  paper  support  is  practically  unlimited. 

2.  Practically  any  desired  color  or  combination  of 
colors  may  be  secured. 

3.  Modifications  of  relative  values  are  made 
more  easily  than  in  any  other  medium  except  oil  and 
bromoil  and  quite  as  readily  as  in  these. 

4 . Modifications  of  total  contrast  are  comparatively 
easy  to  make  in  single  printing  and  the  possibilities  in 
this  direction  are  unlimited  if  multiple  prints  are  made. 

140 


GUM-PLATINUM 


5.  In  single  gum  printing  a practically  lustreless 
surface  may  be  obtained. 

Disadvantages. — 1.  By  reason  of  its  great  flexibility 
gum  is  probably  the  most  difficult  printing  medium  to 
master  completely. 

2.  Single  gum  is  a very  short  scale  medium  and 
does  not  render  shadow  gradations  or  light  grada- 
tions satisfactorily,  its  value  being  confined  to  the 
middle  register.  These  objections,  however,  are  over- 
come in  multiple  printing. 

3.  There  is  a looseness  of  texture  in  a gum  print 
which  militates  against  the  rendering  of  fine  detail, 
this  being  due  partly  to  the  character  of  the  coating 
and  partly  to  the  fact  that  it  is  impossible  to  secure  a 
gum  print  on  a perfectly  smooth  surface,  a slight 
superficial  roughness  being  necessary.  This,  however, 
cannot  be  regarded  as  a disadvantage  to  the  pictorialist, 
who  rarely  if  ever  wishes  fine  definition. 

4.  Duplication  of  results  is  very  difficult,  especi- 
ally if  some  weeks  have  elapsed  between  making  the 
first  and  the  second  prints. 

Gum-Platinum. — If  a gum  print  is  made  over  a 
platinum  by  coating  the  finished  platinum  print  with  a 
gum-pigment  mixture  and  printing  a second  time 
practically  all  the  disadvantages  of  both  mediums  are 
overcome,  since  the  platinum  print  renders  the  grada- 
tions in  the  lights,  which  are  beyond  the  capacity  of  the 
gum,  and  the  gum  print  adds  the  richness  and  grada- 
tions in  the  shadows  which  are  lacking  in  the  platinum, 
it  being  in  addition  comparatively  easy  to  modify 
relative  values  and  being  much  easier  to  master  the 
technique  of  the  process  than  is  the  case  with  gum 

141 


DISCUSSION  OF  VARIOUS  MEDIUMS 


alone.  For  general  photographic  purposes  the  writer  is 
inclined  to  consider  gum-platinum  as  the  best  printing 
medium,  though  special  cases  may  of  course  demand 
other  methods,  and,  as  will  be  seen  later,  oil  and  bromoil 
reach  a higher  level  as  mediums  of  artistic  expression. 

Oil.— Advantages, — -1.  Any  color  or  combination  of 
colors  may  be  used. 

2.  Modifications  of  relative  values  may  be  made 
with  the  utmost  facility. 

3.  Modifications  of  total  contrast  are  made  very 
easily. 

4.  In  some  respects  the  superficial  texture  is  very 
desirable. 

5.  A very  beautiful  quality  of  richness  and  depth 
in  the  shadows  may  be  obtained. 

Disadvantages. — 1.  Delicate  gradations  are  not  so 
well  rendered  as  with  some  other  mediums. 

2.  It  is  practically  an  impossibility  to  obtain  a 
lustreless  surface,  since  the  image  consists  of  an  oily 
pigment  superposed  on  a film  of  gelatine.  The  lustre 
may,  however,  be  greatly  diminished  by  degreasing. 

3.  It  is  somewhat  laborious  to  handle,  since  an 
8"  X 10"  print  will  require  fifteen  minutes  to  an  hour 
for  the  inking  alone,  to  say  nothing  of  the  time  required 
for  sensitizing,  printing,  washing,  and  soaking. 

4.  Duplication  of  results  is  very  difficult. 

Bromoil. — The  advantages  and  disadvantages  of 

bromoil  are  the  same  as  those  of  oil  with  the  following 
additions : 

Advantages. — 6.  It  is  possible  to  make  prints  of 
any  size  from  small  originals  without  the  necessity 
for  making  an  enlarged  negative. 

142 


PHOTOGRAVURE 


Disadvantages . — 5.  The  chemical  processes  in- 
volved in  bromoil  are  somewhat  more  complicated  than 
with  oil  and  there  is  consequently  more  chance  for  failure. 

Oil  and  Bromoil  Transfer. — The  advantages  and 
disadvantages  of  oil  and  bromoil  transfer  are  those  of 
oil  and  bromoil,  except  that  transferring  presents  the 
advantage  of  giving  a lustreless  surface  of  almost  any 
desired  texture,  and  that  it  adds  a further  complication 
with  consequent  additional  opportunity  for  failure. 

Photogravure. — Advantages. — 1.  Practically  any 
color  or  combination  of  colors  may  be  used. 

2.  Modifications  of  total  contrast  are  easily  made. 

3.  There  is  a very  wide  range  of  color  and  texture 
of  stock  available,  although  it  is  not  possible  to  make  a 
photogravure  on  a very  rough  paper,  the  pressure  neces- 
sary being  such  as  to  flatten  out  any  roughness  which 
the  stock  may  possess. 

4.  Absolutely  lustreless  prints  may  be  obtained. 

5.  Great  richness  and  depth  are  easily  secured. 

6.  Duplication  of  results  is  very  easy. 

Disadvantages. — 1.  It  is  rather  expensive. 

2.  It  is  laborious  and  requires  a considerable  degree 
of  manipulative  skill. 

3.  It  does  not  render  the  gradations  in  the  lights 
as  beautifully  as  is  the  case  with  platinum. 

4.  Relative  values  are  not  easily  modified. 

The  writer  is  inclined  to  favor  photogravure  when  a 
lustreless  surface  is  required  in  combination  with  rich- 
ness of  the  shadows,  and  the  rendering  of  delicate 
gradations  in  the  extreme  lights  is  not  important.  If  a 
slight  tone  in  the  lights  is  acceptable  the  gradations 
may  be  well  rendered. 


CHAPTER  X 

TECHNIQUE  OF  PLATINUM* 

It  will  be  found  that  in  this  chapter  and  in  the  one 
dealing  with  the  technique  of  carbon  printing,  the 
method  of  procedure  recommended  varies  somewhat 
from  that  advised  by  the  manufacturers  of  the  papers 
in  question,  this  being  due  to  the  fact  that  the  pictorial 
worker  is  generally  concerned  with  producing  a different 
class  of  results  from  those  desired  by  the  commercial 
photographer,  the  manufacturer’s  instructions  being 
intended  for  the  latter.  In  general,  so  far  as  pictorial 
work  is  concerned,  whether  plates  or  printing  papers 
are  in  question,  the  manufacturer’s  instructions  can 
be  regarded  as  a starting  point  for  the  pictorialist, 
who  will  amplify  and  modify  them  in  order  to  obtain 
the  effects  which  he  desires. 

The  Negative. — Platinum  paper  is  exceedingly 
hygroscopic  and  spoils  very  quickly  if  exposed  to 
moisture,  wherefore  it  is  always  sent  out  by  the  manu- 
facturer in  sealed  tin  tubes  which  contain,  in  addition 
to  the  paper,  a preservative.  This  latter  consists  of  a 
piece  of  asbestos  which  has  been  soaked  in  a solution 
of  calcium  chloride,  a very  hygroscopic  salt,  the  func- 
tion of  the  preservative  being  to  absorb  any  moisture 
which  may  be  in  the  can.  The  preservative  should 
always  be  kept  in  the  can — which  should  be  sealed 
with  a piece  of  adhesive  tape  except  when  withdrawing 
the  paper — and  should  it  become  soft  it  may  be  un- 
wrapped and  heated  in  the  oven  or  over  the  gas  until 


* See  Appendix,  page  296. 
144 


PRINTING 


restored  to  hardness.  It  is  not  well  to  print  platinum 
paper  in  wet  weather,  though  if  it  is  not  too  long 
exposed  to  damp  and  is  developed  immediately  after 
printing  no  harm  will  result.  The  effect  of  damp  is  to 
produce  muddy  tones  and  a general  degradation  of 
the  lights. 

It  is  generally  stated  by  writers  on  the  subject  that 
platinum  demands  a rather  strong  negative,  but  this 
means  simply  that  platinum  has  a long  scale  of  tones 
as  compared  to  bromide  or  gaslight  paper,  and  con- 
sequently if  use  is  to  be  made  of  the  full  possibilities 
of  platinum  printing  the  negative  should  have  a fair 
degree  of  contrast.  It  is  by  no  means  necessary  to  use 
such  a negative,  many  of  the  finest  effects  in  platinum 
being  secured  with  a plate  which  is  decidedly  soft  and 
is  printed  in  either  a high,  medium  or  low  key,  since 
platinum  renders  the  gradations  of  the  negative  per- 
fectly except  in  the  case  of  very  heavy  shadows. 

Printing. — Printing  must  be  done  by  sunlight  or 
by  a very  powerful  artificial  light,  and  should  in  general 
be  continued  until  the  details  in  the  lights  are  faintly 
visible  in  a yellowish  brown  on  the  yellow  ground  of 
the  sensitized  surface,  but  this  statement  can  be  con- 
sidered only  a general  guide,  since  the  depth  of  printing 
will  vary  with  different  circumstances,  some  papers 
being  more  sensitive  than  others,  and  a soft  negative 
when  printed  for  high-keyed  results  giving  a much  less 
distinct  image  than  if  printed  deeper.  Some  of  the 
writer’s  negatives  of  this  class  give  prints  in  which 
before  development  nothing  is  visible  except  a faint 
suggestion  of  the  deepest  shadows,  and  in  such  a case 
the  only  thing  to  do  is  to  make  a test  print  and  note 

10  145 


TECHNIQUE  OF  PLATINUM 

the  time  required.  After  development  of  the  test  slip 
it  can  be  determined  whether  or  not  the  printing  time 
was  correct,  and  necessary  changes  in  the  time  may  be 
made  accordingly.  In  any  case  it  will  be  found  desirable 
to  print  by  time  until  some  experience  in  judging  the 
appearance  of  the  print  is  gained.  No  definite  state- 
ment can  be  given  as  to  printing  time,  since  this  will 
vary  with  the  quality  of  the  negative,  the  kind  of 
paper  used,  the  quality  of  the  light,  the  time  of  year 
and  of  day  and  the  effect  desired,  but  it  may  be  said 
that  an  average  negative,  that  is,  one  which  exhausts 
the  scale  of  the  paper  without  having  any  distinct 
veiling  in  the  shadows  of  the  plate,  will  give  normal 
results  with  three  or  four  minutes’  exposure  to  bright 
sunlight  in  summer.  Some  of  the  writer’s  negatives 
require  not  more  than  twenty  seconds  for  a high-keyed 
print,  whereas  others  may  need  fifteen  or  twenty 
minutes  when  a low-keyed  result  is  desired. 

Development. — Printing  being  complete,  the  next 
step  is  development,  and  this  may  be  carried  out  in  an 
ordinary  room,  merely  taking  care  that  direct  sunlight 
does  not  fall  on  the  print  during  either  development 
or  the  earlier  stages  of  clearing.  The  developer  is 
fundamentally  a saturated  solution  of  potassium  oxa- 
late in  water,  though  other  substances  are  sometimes 
added  to  secure  special  effects.  Such  a solution  may 
be  made  up  by  dissolving  a pound  of  oxalate  in  forty- 
eight  ounces  of  hot  water  and  allowing  it  to  cool,  this 
forming  a stock  solution.  It  may  be  found  with  some 
samples  of  water  that  a slight  cloudiness  results,  which, 
however,  will  settle  to  the  bottom  of  the  bottle,  allow- 
ing the  clear  solution  to  be  poured  off.  The  writer 

146 


DEVELOPMENT 


has  not  found  that  this  cloudiness  does  any  harm. 
The  developer  keeps  well  and  in  fact  improves  with 
use,  giving  richer  prints  when  it  has  been  used  for 
some  time  than  when  it  is  fresh;  hence  used  developer 
should  not  be  thrown  away  but  may  be  kept  up  to 
normal  bulk  by  adding  fresh  stock  solution  from  time 
to  time,  the  clear  yellow  solution  being  poured  off  for 
use  from  the  mud  which  settles  at  the  bottom  of  a used 
developer. 

Some  writers  recommend  development  by  floating 
the  print  face  down  on  the  oxalate  solution,  but  the 
writer  prefers  to  immerse  the  print  bodily  in  the  bath. 
In  ordinary  circumstances  it  is  not  necessary  to  take 
special  precautions  to  flow  the  developer  evenly  over 
the  print,  since  if  development  is  continued  as  far  as  it 
will  go  no  development  marks  will  show,  development 
proceeding  as  far  as  the  light  action  calls  for  and  then 
stopping.  For  special  results,  however,  a hot  developer 
is  sometimes  used  (normal  development  takes  place  at 
room  temperature,  that  is,  65°  to  80°  Fahrenheit),  and 
in  the  event  of  using  hot  developer  care  must  be  taken 
to  avoid  irregular  application,  since  in  this  case  develop- 
ment marks  will  show;  so  when  the  developer  is  hot  it 
must  be  flowed  over  the  print  with  an  even  sweep 
exactly  as  in  developing  a plate. 

Any  air  bubbles  which  may  appear  on  the  print 
during  development  should  be  removed  with  a finger 
or  soft  brush,  as  if  this  is  not  done  they  will  leave 
white  spots  in  the  finished  picture.  Development  will 
be  complete  in  from  ten  seconds  to  two  minutes,  depend- 
ing on  the  temperature  of  the  developer  and  the  paper 
used,  rough  papers  requiring  somewhat  longer  develop- 

147 


TECHNIQUE  OF  PLATINUM 


ment  than  smooth.  If  it  is  desired  to  arrest  development 
before  complete  this  may  be  done,  though  in  such  cases 
it  is  practically  imperative  to  retard  the  action  of  the 
developer,  as  will  be  explained  later,  since  otherwise  it 
is  difficult  to  work  with  sufficient  rapidity.  When 
development  is  complete  the  print  is  lifted  from  the 
tray,  drained  slightly  and  placed  in  a bath  of 


Water , 60  ounces 

Hydrochloric  acid  C.  P. . 1 ounce 


and  allowed  to  remain  there  for  about  five  minutes, 
when  it  is  transferred  to  a second  acid  bath  for  the 
same  length  of  time  and  then  washed  in  running  water 
for  half  an  hour  or  so  and  either  hung  up  to  dry  or 
placed  between  blotters  under  slight  pressure. 

Less  Contrast. — To  obtain  less  contrast  than  nor- 
mal the  print  should  be  given  less  exposure  than 
would  ordinarily  be  the  case  and  be  developed  in  a hot 
solution,  the  temperature  of  the  solution  depending  on 
the  effect  desired,  for  the  hotter  it  is  the  less  will  be  the 
contrast.  In  extreme  cases  the  temperature  of  the 
solution  may  be  raised  as  high  as  the  boiling  point, 
and  it  should  be  noted  that  increase  of  temperature 
gives  warmer  tones  in  the  finished  print. 

Softer  results  may  also  be  obtained  by  adding  a 
very  slight  amount  of  hydrochloric  acid  to  the  devel- 
oper, a few  drops  of  the  1:60  clearing  bath  in  sixteen 
ounces  of  the  oxalate  solution  having  a noticeable  effect. 

More  Contrast. — The  variations  possible  in  the 
direction  of  increased  contrast  are  greater  than  in 
the  direction  of  diminishing  contrast,  and  numerous 
methods  are  available,  the  simplest  being  to  dilute  the 
developer,  a slight  increase  of  exposure  being  then 
148 


MORE  CONTRAST 

necessary.  If,  however,  more  than  five  volumes  of 
water  are  used  to  one  volume  of  stock  solution  a certain 
granularity  of  the  print  is  likely  to  result.  This  granu- 
larity may  also  be  a result  of  using  the  developer  too 
cold.  If  insufficient  contrast  is  obtained  in  this  manner 
the  stock  solution  may  be  diluted  with  an  equal  volume 
of  glycerine  instead  of  water  and  the  print  be  exposed 
considerably  longer  than  for  normal  results.  The 
glycerine  slows  the  development  markedly,  so  that  full 
development  may  require  from  five  to  ten  minutes,  but 
instead  of  permitting  the  print  to  develop  fully  it  is 
taken  from  the  developer  just  before  the  desired  depth 
has  been  reached  and  is  drained  slightly,  rinsed  under  a 
rather  vigorous  stream  of  water  and  placed  in  the 
clearing  bath.  If  rinsing  is  omitted  the  clearing  bath 
will  penetrate  the  developer  irregularly  so  that  develop- 
ment is  arrested  in  places  while  it  continues  in  other 
areas,  and  uneven  or  streaky  results  follow.  This 
method  is  so  uncertain  and  so  difficult  to  gauge  ac- 
curately that  the  writer  prefers  not  to  use  it.  A method 
which  seems  decidedly  preferable  to  diluting  the 
developer  with  glycerine  is  to  add  to  the  stock  de- 
veloper a slight  amount  of  potassium  bichromate,  five 
grains  of  the  salt  to  sixteen  ounces  of  the  developer 
producing  a marked  effect,  and  further  additions  in- 
creasing contrast  to  practically  an  unlimited  extent. 
Printing  must  be  deeper  than  normal  in  proportion  to 
the  amount  of  bichromate  added.  It  should  be  noted 
that  although  a diluted  developer  continues  to  work  as 
well  after  use  as  when  fresh  the  bichromate  becomes 
exhausted  with  use  and  fresh  additions  to  the  solution 
must  be  made.  Great  increase  of  contrast  may  be 

149 


TECHNIQUE  OF  PLATINUM 


secured  in  the  following  manner,  which  will  give  a 
normal  result  from  a mere  ghost  of  a negative  and 
practically  a silhouette  from  a normal  plate.  Printing 
is  continued  until  the  entire  print  shows  a bronze  color 
or  even  until  reversal  has  taken  place,  the  shadows 
appearing  lighter  than  the  lights,  and  the  print  is  then 
developed  in  clear  water,  cold  water  requiring  deeper 
printing  and  giving  more  contrast  than  hot.  This 
method  is  almost  certain  to  produce  granularity  of  the 
print,  which  may  or  may  not  be  desirable. 

Warmer  Tones. — As  has  been  stated  above,  a 
slight  increase  in  warmth  of  tone  is  secured  by  using  a 
hot  developer,  and  commercial  papers  may  be  obtained 
in  which  the  sensitizing  has  been  such  as  to  give  sepia 
prints.  The  writer,  however,  prefers  to  use  the  black 
papers  and  secure  warmer  tones  by  modifying  the 
developer,  since  the  shadows  of  a print  on  sepia 
paper  are  apt  to  look  rather  thin  and  uninteresting, 
whereas  very  desirable  rich  effects  of  any  desired 
warmth  may  be  obtained  on  the  regular  black  papers. 
The  addition  of  a slight  amount  of  bichloride  of  mer- 
cury to  the  developer  produces  a warm  black,  and 
further  additions  may  increase  the  warmth  of  color  up 
to  a full  sepia.  Of  course,  the  amount  of  the  salt  added 
will  depend  on  the  effect  desired  by  the  worker,  and  it 
will  be  well  to  begin  with  twenty  grains  of  the  bi- 
chloride to  sixteen  ounces  of  the  stock  solution  and  pro- 
ceed from  this.  Some  writers  say  that  the  addition  of 
bichloride  of  mercury  causes  instability  of  the  results, 
but  the  writer  has  not  found  this  to  be  the  case  in  his 
own  practice,  which  extends  over  a period  of  about  ten 
years.  It  is,  of  course,  admitted  that  this  is  too  short 
150 


WARMER  TONES 


a time  to  determine  by  observation  whether  or  not  a 
print  is  permanent,  but  it  has  been  stated  on  the  au- 
thority of  von  Hlibl  that  the  image  in  a mercury  devel- 
oped platinum  print  consists  of  pure  metallic  platinum, 
the  warmth  of  color  being  due  to  a difference  in  the 
size  of  the  grains  of  metal  deposited.  This  seems  a 
probable  explanation,  and  if  it  is  correct  there  is,  of 
course,  no  reason  to  fear  fugitiveness  of  a brown  or 
sepia  platinum.  The  writer  believes  that  when  mer- 
cury-developed platinum  prints  prove  unstable  this 
instability  is  due  to  insufficient  clearing,  so  that  some 
iron  salts  are  left  remaining  on  the  paper,  these  salts  of 
course  darkening  when  exposed  to  light.  This  belief  is 
supported  by  the  fact  that  most  writers  recommend 
clearing  such  prints  for  not  more  than  two  minutes  in 
a single  bath  of 


Water 300  ounces 

Hydrochloric  acid  C.P 1 ounce 


since  it  is  undeniably  the  case  that  a normal  clearing 
bath  will  remove  some  of  the  warmth  resulting  from 
the  use  of  mercury.  Evidently  since  this  is  so,  if  the 
normal  clearing  bath  is  to  be  employed  more  of  the 
bichloride  must  be  used  to  secure  a given  warmth  of 
tone  than  when  the  weaker  acid  bath  is  to  be  employed. 

Colder  Tones. — Colder  tones  may  be  secured  by 
using  a developer  made  up  as  follows: 


Water 16  ounces 

Potassium  oxalate 3 ounces 

Monobasic  potassium  phosphate. 1 ounce 


Printing  must  be  slightly  deeper  for  this  developer  than 
for  the  normal  solution  and  a slight  increase  of  con- 
trast will  result. 


151 


TECHNIQUE  OF  PLATINUM 


Old  Paper. — Platinum  paper  as  sent  out  by  the 
makers  is  always  contained  in  a sealed  tin  tube  with 
preservative  as  noted  above  and  should  always  be  kept 
in  this  manner  when  not  in  actual  use.  If  the  paper  is 
not  kept  dry  it  deteriorates  rapidly  and  even  when  care- 
fully packed  it  will  deteriorate  in  time.  Stale  paper  if 
treated  normally  gives  muddy  prints  having  degraded 
lights,  even  the  edge  of  the  print  which  is  protected  by 
the  rebate  of  the  printing  frame  being  considerably 
darker  than  the  paper  base.  The  extent  of  this  de- 
gradation depends  on  the  age  of  the  paper  and  it  is 
generally  considered  that  paper  six  months  old  will  not 
give  the  character  of  print  desired  by  commercial  pho- 
tographers. The  degradation  of  the  lights  which  results 
from  age  may,  however,  be  very  pleasing  for  pictorial 
purposes,  especially  if  bichloride  of  mercury  is  used 
in  the  developer,  but  if  bright  prints  are  desired 
they  may  be  secured  on  paper  which  has  deteriorated 
to  only  a slight  extent  by  using  glycerine  in  the  devel- 
oper and  arresting  development  before  it  is  complete, 
as  explained  above.  If  the  paper  is  too  old  for  this  it 
may  still  be  made  to  give  bright  prints  by  the  use  of 
bichromate  of  potash  in  the  developer,  the  amount  of 
the  salt  required  depending,  of  course,  on  the  age  of 
the  paper.  This  chemical  is  capable  of  producing  such 
an  increase  of  clearness  that  the  writer  has  made  prints 
of  snow  pictures  with  strong  sunlight  (than  which  no 
effect  demands  greater  brilliance)  on  platinum  paper 
which  was  nearly  two  years  old. 

General  Remarks. — A platinum  print  should  ap- 
pear slightly  lighter  in  the  developer  than  is  desired  in 
the  finished  result,  since  it  dries  a little  darker  than  it 

152 


GENERAL  REMARKS 


appears  when  wet.  If  it  is  desired  to  restore  the  bril- 
liance which  the  print  has  when  wet  this  may  be  accom- 
plished by  varnishing  the  dried  print,  various  substances 
being  used  for  this  purpose.  French  picture  varnish 
thinned  with  alcohol  will  give  a lustrous  surface  with- 
out changing  the  color  of  the  print,  as  will  also  a bath 
made  up  of 

Water 16  ounces 

Gelatine }/%  ounce 

The  gelatine  must  be  swelled  in  cold  water  and  dis- 
solved by  gentle  heat,  and  the  print  is  dipped  into  it 
while  the  solution  is  still  warm,  and  is  then  hung  up  to 
dry.  The  amount  of  lustre  added  by  this  method  de- 
pends on  the  temperature  of  the  gelatine  solution,  since 
if  this  is  allowed  to  cool  a heavier  deposit  forms  on  the 
print  than  if  the  bath  is  used  hot.  If  a slight  increase 
of  warmth  in  the  lights  and  half  tones  is  not  objection- 
able— and  it  is  often  desirable,  especially  in  portraits 
or  in  sunny  landscapes — the  print  may  be  varnished 
with  Johnson’s  or  Old  English  floor  wax  applied  with 
a rather  stiff  brush,  the  wax  being  polished  with  a 
nail  brush  or  small  scrubbing  brush.  Butcher’s  Bos- 
ton Polish  may  also  be  used,  but  imparts  a decidedly 
pink  tint  to  the  print,  whereas  the  other  polishes  give 
a pure  yellow,  the  Old  English  being  deeper  in  color 
than  Johnson’s.  A very  desirable  increase  of  richness 
is  secured  by  applying  floor  wax  to  the  print  and  either 
melting  it  in  over  a gas  flame — taking  care  not  to  set  it 
on  fire — or  ironing  it  in  with  a hot  flat  iron,  in  which 
case  the  print  should  be  laid  face  down  on  a clean  piece 
of  paper  and  the  iron  applied  to  the  back. 

It  has  been  said  that  the  writer  does  not  approve 

153 


TECHNIQUE  OF  PLATINUM 


of  using  glycerine  in  combination  with  brief  develop- 
ment to  secure  increase  of  contrast,  but  the  treatment 
with  glycerine  undeniably  gives  richer  blacks  and  a more 
beautiful  quality  than  is  obtained  with  the  normal  de- 
veloper. In  using  it  for  this  purpose  development 
should  be  allowed  to  proceed  until  complete  and  it 
should  be  noted  that  a glycerine-diluted  developer 
does  not  keep  if  heated  above  140°  Fahrenheit. 

Platinum  paper  may  be  bought  in  cut  sizes,  twelve 
sheets  in  a package,  or  in  rolls,  a full  roll  being  twenty 
inches  wide  and  twenty-six  feet  long,  as  well  as  in  half 
rolls,  twenty  inches  wide  and  thirteen  feet  long.  For 
the  small  worker  it  will  be  more  convenient  to  buy  it 
in  cut  sizes,  but  if  any  considerable  amount  of  work  is 
to  be  done  it  is  cheaper  to  buy  the  rolls  and  cut  them 
to  size  as  desired.  It  is  distinctly  worth  while  to  save 
waste  platinum  prints  and  clippings  of  the  paper,  since 
these  may  be  refined  and  the  refiners  will  normally  pay 
at  least  twenty-five  cents  per  pound  for  such  waste. 
Used  developer  also  contains  a certain  amount  of  plati- 
num and  may  be  sold,  in  addition  to  which  the  clearing 
baths  contain  platinum  enough  to  make  it  worth  while 
saving  them  if  a large  amount  of  work  is  to  be  done,  as 
in  commercial  establishments,  but  for  the  average 
amateur  the  cost  and  trouble  of  recovering  the  plati- 
num from  the  acid  would  amount  to  more  than  the 
value  of  the  metal  recovered. 

Some  workers  experience  great  trouble  with  “comet 
marks,”  that  is,  small  white  streaks  which  appear  dur- 
ing development  and  cannot  be  removed  except  by 
spotting  the  finished  print.  The  writer  has  never  had 
any  difficulty  of  this  sort  except  in  a few  minor  in- 

154 


HAND-SENSITIZED  PLATINUM 


stances,  but  observation  leads  him  to  believe  that  it 
arises  from  one  or  more  of  three  causes.  A saturated 
solution  of  oxalate  of  potash  will  become  super-sat- 
urated through  evaporation  of  the  water  during  ex- 
posure to  the  air,  and  some  of  the  salt  will  crystallize 
out  and  fall  to  the  bottom  of  the  bottle,  together  with 
other  chemicals,  the  latter  being  removed  from  the 
paper  during  development.  If  the  bottle  is  shaken  or 
if  the  solution  is  not  carefully  decanted  some  of  these 
crystals  will  be  carried  into  the  developing  tray  and 
may  conceivably  cause  marks.  The  second  cause  is  the 
use  of  dirty  trays,  some  chemicals  remaining  in  the 
trays  from  former  work.  All  trays,  for  whatever  pur- 
pose they  are  used,  should  be  given  a thorough  scour- 
ing with  Gold  Dust  before  being  put  away.  The  third 
cause  is  the  formation  of  a scum  on  the  surface  of  the 
developer  in  the  tray.  This  may  be  broken  up  by 
rocking  the  tray  just  before  immersing  the  print. 

Hand  - sensitized  Platinum. — The  operation  of 
sensitizing  platinum  paper  is  an  exceedingly  simple 
one,  being  within  the  capacity  of  any  person  who  will 
follow  instructions  with  even  moderate  care. 

Almost  any  paper  may  be  used  for  sensitizing, 
though  some  papers  will  be  found  too  absorbent  and 
others  too  heavily  sized.  Papers  which  can  be  recom- 
mended are  the  Strathmore  Drawing,  Charcoal,  and 
Detail  papers  of  the  Strathmore  Paper  Co.,  the  various 
grades  of  Japanese  vellum  and  hand-made  Spanish 
papers  sold  by  the  Japan  Paper  Co.,  of  New  York  City, 
as  well  as  various  writing  and  note  papers.  Of  course, 
the  possible  variations  of  color  and  texture  are  almost 
unlimited. 


155 


TECHNIQUE  OF  PLATINUM 


Three  stock  solutions  are  required,  as  follows: 


1.  Water  (hot,  distilled) 2 ounces 

Oxalic  acid  16  grains 

Ferric  oxalate  (fresh,  green  scales) 240  grains 

2.  Water  (hot,  distilled) 2 ounces 

Oxalic  acid 16  grains 

Ferric  oxalate  (fresh,  green  scales) 240  grains 

Potassium  chlorate 4 grains 

3.  Water  (hot,  distilled) i%  ounces 


Potassium  chloroplatinite 219  grains  ounce) 

These  should  be  kept  in  amber  bottles  or  in  the  dark, 
since  they  are  sensitive  to  light.  For  use  they  are 
mixed  in  the  proportions  given  below,  a medicine  drop- 
per or  a minim  graduate  being  used  for  measuring.  If 
a medicine  dropper  is  used  it  should  be  washed  in  clean 
water  after  measuring  each  of  the  solutions,  and  some 
workers  prefer  to  keep  three  droppers,  one  for  each 
solution,  the  objection  to  this  method  being  that  it 
seldom  happens  that  two  droppers  measure  drops  of 
the  same  size.  If  three  droppers  are  used,  they  should, 
of  course,  be  checked  by  means  of  a standard  graduate. 
It  will  be  seen  from  what  follows  that  increasing  the 
proportion  of  Solution  2 increases  contrast  in  the  print, 
and  it  is  possible  to  get  very  soft  prints  from  a strong 
negative  or  very  strong  prints  from  a flat  plate  by  vary- 
ing the  proportions.  Reading  over  these  formulae  it 
will  be  apparent  that  the  chemical  which  operates  to 
increase  contrast  is  potassium  chlorate  and  in  extreme 
cases  further  additions  of  this  salt  may  be  made.  In 
preparing  the  solutions  care  should  be  taken  to  see  that 
the  iron  salt  is  ferric  and  not  ferrous,  and  this  salt 
should  have  the  form  of  dry,  bright  green  scales;  if  the 
scales  are  brown  or  show  any  tendency  to  stick  together 
the  sample  should  be  rejected.  Care  should  also  be 
taken  to  see  that  the  potassium  chloroplatinite  is  ob- 
156 


HAND-SENSITIZED  PLATINUM 


tained,  and  this  should  be  in  the  form  of  bright  red 
crystals,  the  chloroplatinite,  which  is  yellow,  not  being 
useful  for  this  purpose. 

The  paper  to  be  sensitized  should  be  cut  about  one 
inch  larger  each  way  than  the  finished  print  is  to  be, 
and  is  then  pinned  by  the  four  corners  to  a horizontal 
board.  The  proper  quantity  of  each  solution  is  meas- 
ured out  according  to  the  result  desired,  as  indicated 
in  the  following  table: 


A.  For  very  soft  prints. 

1  22  minims 

2  0 minims 

3  24  minims 

B.  For  stronger  prints. 

1  18  minims 

2  4 minims 

3  24  minims 

C.  For  average  results. 

1  14  minims 

2  8 minims 

3  24  minims 

D.  For  strong  prints. 

1  10  minims 

2  12  minims 

3  24  minims 

E.  For  extreme  contrast. 

1 0 minims 

2. 22  minims 

3 24  minims 


These  solutions  are  then  mixed  thoroughly  in  a graduate 
and  poured  on  the  paper,  being  spread  by  means  of 
a damp  brush  which  is  worked  back  and  forth  over  the 
surface  of  the  paper  until  the  latter  begins  to  show  signs 
of  surface-drying,  when  it  is  allowed  to  remain  for 
about  five  minutes  and  is  then  made  bone  dry  over  a 
stove  or  gas  jet,  care  being  taken  that  it  is  not  scorched. 
It  should  be  noted  that  the  sensitizer  will  scorch  before 

157 


TECHNIQUE  OF  PLATINUM 


the  paper  does  so,  this  fault  as  a rule  not  being  observ- 
able until  the  print  is  developed,  when  it  shows  as 
patches  darker  than  they  should  be.  After  drying  the 
paper  is  trimmed  to  size  and  stored  in  a platinum  can 
with  preservative  until  it  is  to  be  used. 

The  processes  of  printing,  development,  clearing, 
and  washing  are  the  same  as  with  the  commercial 
papers,  except  that  the  hand-sensitized  paper  prints 
more  slowly  than  the  commercial  and  that  the  image  is 
less  clearly  visible. 

Any  flat  camel-hair  or  sable  brush  may  be  used  for 
sensitizing,  though  most  desirable  are  the  flat  Japanese 
paint  brushes.  It  will  be  found  that  after  several  prints 
have  been  sensitized  the  brush  contains  enough  sen- 
sitizer to  treat  another  small  piece  of  paper  and  this 
should  be  done  in  order  to  save  as  much  of  the  plat- 
inum salt  as  possible.  The  chief  point  of  importance  is 
the  drying  of  the  paper,  which  for  most  papers  should 
occupy  not  less  than  five  nor  more  than  ten  minutes, 
though  it  will  be  found  that  some  very  soft  papers  will 
tend  to  give  degraded  lights  unless  dried  more  rapidly 
than  this,  and  that  with  some  heavily  sized  papers  it 
will  be  necessary  to  dry  them  more  slowly  in  order  to 
keep  the  sensitizer  from  washing  off  in  the  developer. 
A platinum  sensitizer  is  unlike  a gum  coating  in  that 
there  is  practically  no  danger  of  getting  a streaky  result. 
If  several  pieces  are  to  be  sensitized  it  will  be  more  con- 
venient to  obtain  the  paper  in  large  sheets  and  sensi- 
tize it  in  that  form,  afterward  cutting  it  to  size,  rather 
than  to  sensitize  each  piece  separately.  Some  papers, 
such  as  the  softer  vellums  and  the  hand-made  Bar- 
celona paper,  will  require  sizing  if  multiple  prints  are 

158 


HAND-SENSITIZED  PLATINUM 


to  be  made,  but  this  is  not  generally  the  case  with  draw- 
ing or  writing  papers.  If,  however,  it  is  necessary  to 
size,  a thin  starch  paste  may  be  brushed  over  the  paper 
after  the  first  print  has  been  developed,  cleared,  washed 
and  dried,  this  size  being  allowed  to  dry  thoroughly 
before  applying  the  second  sensitizer. 

It  will  not  be  easy  to  get  rich  blacks  with  a single 
sensitizing,  but  with  two  applications  of  sensitizer  this 
may  be  accomplished,  and  the  second  sensitizer  may 
be  put  on  immediately  after  drying  the  first  or  if  pre- 
ferred the  paper  may  be  printed,  developed,  cleared, 
washed  and  dried  and  the  second  application  of  sen- 
sitizer take  the  form  of  a second  printing,  it  being  of 
course  necessary  to  register  to  print  and  to  expose 
by  time.  Various  methods  for  securing  registration 
are  given  in  the  chapters  on  gum,  gum-platinum,  and 
carbon  printing.  Of  course,  the  second  printing  may 
be  the  same  quality  as  the  first  or  may  be  either  lighter 
or  darker  according  to  the  result  desired,  and  if  it 
seems  best  a different  sensitizing  mixture  may  be  used 
for  the  second  printing. 

Especially  beautiful  are  prints  on  various  tissues, 
but  these  are  exceedingly  difficult  to  handle,  since  it  is 
not  easy  to  observe  either  the  depth  of  printing  or  the 
manner  in  which  development  progresses,  so  that  little 
can  be  told  about  the  result  until  the  print  has  been 
dried  and  ironed.  It  is  therefore  practically  imperative 
to  print  by  time  when  using  such  papers,  and  in  most 
cases  a tissue  will  require  sizing  before  the  first  sensi- 
tizing, though  this  does  not  hold  good  of  the  vellum 
tissues. 


CHAPTER  XI 

TECHNIQUE  OF  CARBON 

There  is  a popular  impression  to  the  effect  that 
carbon  is  a difficult  process  to  handle,  but  this  is  by  no 
means  the  case,  for  although  it  is  more  laborious  than 
platinum,  it  does  not  require  any  high  degree  of  manip- 
ulative skill,  and  calls  for  less  actual  labor  than  gum, 
oil,  or  photogravure. 

Theory. — If  a colloid  substance  such  as  gelatine, 
gum  arabic  or  albumen  is  sensitized  with  potassium, 
sodium,  or  ammonium  bichromate  and,  after  drying, 
is  exposed  to  light,  the  colloid  becomes  insoluble  in 
water.  If  a dry  pigment  is  incorporated  with  the  col- 
loid and  a thin  film  is  spread  on  a sheet  of  paper,  this 
film  being  sensitized  and  printed  under  a negative, 
then,  on  washing  in  water,  the  portions  which  have 
been  acted  on  by  light  will  resist  the  action  of  the  water 
and  remain  on  the  paper,  holding  their  quota  of  pig- 
ment, but  those  portions  which  have  been  protected 
from  light,  being  soluble,  will  wash  off  the  paper,  tak- 
ing their  pigment  with  them.  Hence  there  results  a 
print  in  which  the  gradations  are  represented  by  vary- 
ing thickness  of  colloid  and  pigment. 

In  carbon  printing  the  colloid  used  is  gelatine,  and, 
since  this  is  in  no  case  soluble  in  cold  water,  hot  water 
(about  110°  Fahrenheit)  must  be  employed  for  devel- 
oping. 

The  Tissue. — The  term  “ tissue”  is  rather  a mis- 
nomer, since  the  paper  supplied  for  carbon  work  con- 

160 


SENSITIZING  BY  IMMERSION 


sists  of  a stout  backing  which  carries  a heavy  film  of 
gelatine  and  pigment,  the  whole  being  stiff  and,  when 
dry,  brittle.  The  tissue  is  supplied  in  forty  or  more 
different  colors,  and  may  be  bought  either  in  cut  sizes 
(5X7,  6^XS3^,  and  8X10  are  the  only  sizes  supplied) 
or  in  rolls  thirty  inches  by  twelve  feet.  If  much  work 
is  to  be  done  the  rolls  are  somewhat  cheaper,  but  the 
cut  sizes  are  easier  to  handle,  since  they  are  packed 
flat  and  have  less  tendency  to  curl.  The  tissue  should 
be  either  bought  or  cut  at  least  an  inch  larger  each  way 
than  the  negative  to  be  printed  from,  this  being  im- 
perative for  multiple  printing  (as  will  be  seen  later) 
and  advisable  in  any  case,  since  if  the  tissue  is  cut  to 
size  just  before  printing  it  is  less  likely  to  give  trouble 
by  frilling  during  the  subsequent  manipulations  than 
if  the  edge  has  been  cut  for  some  time. 

Sensitizing  by  Immersion. — Formulae  innumerable 
are  given  for  sensitizing,  but  the  one  which  the  writer 
finds  most  desirable  is  the  following,  slightly  modified 
from  that  worked  out  by  Henry  W.  Bennett: 

Water,  hot 30  ounces 

Potassium  bichromate 960  grains 

Dissolve,  and  when  cool  add 

Citric  acid 240  grains 

When  dissolved  add,  a little  at  a time,  with  stirring. 

Stronger  ammonia.  . . .q.  s.  to  turn  from  orange  to  yellow. 

Add  water  to  make  total  bulk  64  ounces.  Bottle  and 
leave  uncorked  for  twenty-four  hours  to  allow  any  excess 
of  ammonia  to  pass  off.  Use  between  60°  and  75°  E 

This  sensitizer  keeps  indefinitely,  but  should  be 
filtered  after  use.  To  sensitize,  pour  an  inch  or  so  of 
the  solution  into  a tray  and  immerse  the  tissue,  face  up, 
breaking  any  air-bubbles  that  may  form  on  either  front 
or  back,  and  keeping  the  tissue  completely  immersed. 
At  the  expiration  of  two  and  a half  minutes  from  the 
n 161 


TECHNIQUE  OF  CARBON 


first  immersion  withdraw  the  tissue,  lay  it  face  down 
on  a clean  piece  of  glass  or  a clean  ferrotype  plate,  and 
squeegee  lightly  to  expel  the  excess  of  sensitizer.  A 
scraper  squeegee  should  be  used  instead  of  a roller, 
and  the  kind  sold  for  cleaning  windows  is  the 
best,  the  photographic  squeegees  being  too  stiff. 
If  glass  is  used  the  tissue  should  be  stripped  off  and 
hung  up  in  the  dark  to  dry,  but  if  the  ferrotype  plate 
is  employed  the  tissue  may  be  allowed  to  dry  on  it,  and 
this  is  recommended,  since  the  tissue  will  then  be  less 
likely  to  curl,  and,  the  surface  having  been  protected 
from  air  while  drying,  the  tissue  will  be  in  better  work- 
ing condition.  When  dry  the  tissue  will  strip  from  the 
ferrotype  plate  very  easily,  provided  the  plate  was 
clean,  though  dirt  or  finger-marks  may  cause  it  to 
stick.  Sensitizing  may  be  done  in  an  ordinary  room, 
since  the  tissue  is  not  sensitive  until  dry,  but  drying 
should  take  place  in  the  dark,  for  when  dry  the  tissue 
is  at  least  as  sensitive  as  P.  O.  P.  If  the  atmospheric 
conditions  are  such  that  drying  requires  more  than  eight 
or  ten  hours  the  tissue  may  show  a tendency  to  become 
insoluble  without  exposure  to  light,  and  in  extreme 
cases  may  be  quite  useless.  The  sensitized  tissue  does 
not  remain  in  first-class  condition  for  more  than  twenty- 
four  hours,  and  in  the  course  of  a week  or  ten  days  be- 
comes entirely  useless  through  insolubilization,  even 
though  protected  from  light  and  air  in  a platinum  tin, 
with  preservative.  Without  this  precaution  deterior- 
ation is  more  rapid. 

Longer  immersion  or  a stronger  bath  gives  a quicker 
printing  tissue  and  softer  prints,  briefer  immersion  or  a 
weaker  bath  giving  a slower  tissue  and  more  contrast, 

162 


THE  STYGIAN  SHORE 
BY  H.  Y.  SUMMONS 
From  a Carbon  Print 


QUICK-DRYING  SENSITIZER 


but  these  variations  are  not  recommended,  since  the 
results  are  somewhat  indeterminate.  The  normal  bath 
is  a 3 per  cent,  solution,  and  the  sensitizer  should  in  no 
case  be  weaker  than  1 per  cent,  or  stronger  than  7 per 
cent. 

Bichromate  Poisoning. — Some  individuals  are 
sensitive  to  bichromates,  contact  with  these  salts  pro- 
ducing an  annoying  and  sometimes  painful  skin  irrita- 
tion, which  in  extreme  cases  may  be  very  serious.  The 
writer  has  never  experienced  any  trouble  from  this 
source,  but  is  acquainted  with  a photographer  who  suf- 
fered for  more  than  a year  with  a recurrent  skin  erup- 
tion covering  the  hands,  forearms,  and  part  of  the  face, 
this  eruption  being  so  serious  as  to  prohibit  absolutely 
all  photographic  activity  and  almost  to  incapacitate 
the  individual  from  any  work  whatever.  Should  the 
carbon  worker  notice  any  swelling,  redness,  or  soreness 
of  the  fingers,  especially  around  the  base  of  the  nails, 
he  should  at  once  abandon  the  use  of  bichromate  and 
consult  a skin  specialist.  However,  the  use  of  rubber 
gloves  is  a certain  preventive  of  trouble,  and  is  to  be 
recommended,  since  no  one  can  tell  whether  or  not  he 
is  sensitive  except  by  experience 

Quick-drying  Sensitizer. — It  will  be  seen  that 
unless  sensitizing  is  done  early  in  the  morning  it  will 
not  be  possible  to  print  on  the  same  day  if  the  tissue  is 
sensitized  by  immersion,  but  it  is  possible  to  sensitize 
in  such  a manner  that  the  tissue  will  dry  within  half 
an  hour  or  an  hour,  by  means  of  a quick-drying  sensi- 
tizer. This  may  be  prepared  by  the  worker,  but  it  is 
better  to  obtain  the  commercial  solution.  To  use  this 
sensitizer  the  tissue  is  fastened  face  up  on  a piece  of 

163 


TECHNIQUE  OF  CARBON 


glass  by  means  of  wooden  clips,  the  sensitizer  is  poured 
to  the  depth  of  half  an  inch  or  so  into  a tray  and  is  ap- 
plied to  the  tissue  by  means  of  a Blanchard  brush. 
This  consists  of  a piece  of  glass  with  a double  thickness 
of  canton  or  outing  flannel  folded  over  one  edge  and 
held  in  place  by  a string  or  rubber  band.  The  brush, 
which  should  be  as  long  as  the  long  way  of  the  tissue,  is 
dipped  into  the  sensitizer,  drained,  and  drawn  several 
times  over  the  tissue,  alternating  downward  and  cross 
strokes.  Firm  but  not  heavy  pressure  should  be  used, 
and  if  a definite  number  of  strokes  is  adhered  to  the 
printing  speed  of  different  pieces  of  tissue  will  be  alike. 
The  chief  danger  in  brush  sensitizing  is  that  streaky 
prints  will  result  from  having  the  brush  either  too  wet 
or  too  dry,  and  only  experience  can  determine  the 
proper  condition.  Any  unused  sensitizer  remaining  in 
the  tray  should  be  thrown  away. 

Should  the  worker  desire  to  prepare  his  own  spirit 
sensitizer  the  following  method  will  be  found  satis- 
factory. 


Stock  solution: 

Water 4 ounces 

Sodium  bichromate. 1920  grains 

For  use  take: 

Stock  solution 2 drams 

Alcohol  95  per  cent  to  make . 2 ounces 


More  or  less  of  the  stock  solution  may  be  used  in  order 
to  decrease  or  increase  contrast. 

Printing. — The  printing  time  must  be  determined 
by  some  other  means  than  inspection,  since  carbon 
does  not  give  a visible  image  in  the  printing  frame  ex- 
cept in  the  case  of  some  of  the  lighter  colors,  the  image 
even  then  being  too  indefinite  to  serve  as  a guide. 

164 


PRINTING 


Various  forms  of  actinometer  are  recommended  by  dif- 
ferent authors,  but  the  present  writer  finds  the  simplest 
method — which  is  quite  satisfactory — to  be  to  make  a 
proof  on  P.  0.  P.  and  to  print  the  carbon  tissue  for  the 
same  time  as  is  required  for  proofing.  This  is  not 
quite  accurate,  since  the  speed  of  various  batches  of 
P.  O.  P.,  even  those  of  the  same  brand,  may  vary  con- 
siderably, and  different  tissues  have  different  printing 
speeds,  but  carbon  fortunately  has  a good  deal  of  lati- 
tude, and  even  serious  errors  of  exposure  may  be  cor- 
rected in  development.  The  mezzotint  tissues  should 
be  printed  only  half  this  time,  and  the  Ivory  Black 
only  three-quarters,  but  this  method  will  serve  as  a 
guide,  and  will  be  found  reasonably  accurate,  at  all 
events  in  the  case  of  the  black  tissues. 

Since  the  print  must  be  transferred  to  another  sheet 
of  paper  (or  other  support)  for  development,  it  follows 
that  it  will  be  reversed  as  regards  right  and  left  if 
printed  in  the  usual  manner.  Of  course,  if  the  negative 
is  on  film  or  paper  it  may  simply  be  put  into  the  frame 
backward  and  the  tissue  placed  in  contact  with  the 
back,  when  the  finished  print  will  be  the  right  way 
round.  If  the  negative  is  on  a glass  plate  and  the  print 
is  made  from  the  back  some  softening  of  outlines  will 
result  if  printing  takes  place  in  a diffused  light,  that 
is,  on  a dull  day  or  in  the  shade,  but  if  direct  sunlight 
is  used  and  the  frame  is  not  moved  during  exposure 
diffusion  will  probably  not  be  apparent. 

In  order  that  the  print  may  develop  satisfactorily, 
without  frilling,  it  is  necessary  to  provide  a safe-edge, 
that  is,  a strip  of  the  tissue  one-eighth  inch  or  more  in 
width  around  the  margin  must  be  entirely  protected 

165 


TECHNIQUE  OF  CARBON 


from  light,  and  this  may  be  done  by  the  rebate  of  the 
printing  frame,  by  a line  of  opaque  run  around  the 
edge  of  the  negative,  by  a strip  of  passepartout  tape 
gummed  to  the  plate,  or  by  a cardboard  mask.  The 
writer’s  own  practice  is  to  depend  on  the  rebate  of  the 
frame  in  single  printing  and  in  multiple  printing  on  a 
mask,  the  mask  also  furnishing  a very  convenient 
means  for  insuring  registration  of  the  successive  prints. 
Whatever  the  form  of  the  mask,  it  is  desirable  that  it  be 
separated  from  the  tissue  by  about  one-sixteentli  inch, 
a slight  vignetting  action  facilitating  the  subsequent 
operations. 

Need  for  Transferring. — Since  the  effect  of 
printing  is  to  render  the  gelatine  insoluble  in  inverse 
proportion  to  the  densities  of  the  gradations  of  the 
negative,  it  follows  that  as  the  print  comes  from  the 
frame  it  has  a layer  of  insoluble  gelatine  over  the  entire 
surface,  except  perhaps  in  the  highest  lights,  the  in- 
solubilization extending  to  different  depths  in  the 
film,  depending  on  the  amount  of  light  that  has  pene- 
trated the  corresponding  portions  of  the  negative. 
Therefore  it  will  be  difficult  for  the  hot  water  to  pene- 
trate to  the  soluble  gelatine,  and  having  done  so,  it  will 
detach  the  entire  film  from  the  paper  backing  except 
in  those  portions  where  the  light  has  acted  clear  through 
the  film.  If,  however,  the  gelatine  film  is  transferred 
to  another  piece  of  paper  so  that  what  was  originally 
the  outer  layer  is  now  next  the  paper,  then  the  water 
can  easily  reach  the  soluble  parts,  and  will  dissolve 
them  away  without  affecting  the  parts  that  have  been 
acted  upon  by  light. 

Making  Transfer  Paper. — The  transfer  paper 

166 


MAKING  TRANSFER  PAPER 


consists  simply  of  a sheet  of  paper  which  has  been 
coated  with  a film  of  insoluble  gelatine,  and  may  be 
bought  already  prepared,  but  the  worker  is  strongly 
advised  to  make  his  own,  since  he  may  then  choose  any 
color  and  surface  texture  desired,  and  in  addition  to 
this  he  will  find  the  home-made  paper  more  reliable 
than  the  commercial. 

Making  the  transfer  paper  is  a simple  and  easy 
operation,  and  is  carried  out  as  follows.  Any  paper 
which  does  not  disintegrate  in  hot  water  may  be  used, 
though  a rather  stout  one  is  preferable  to  a thin,  any 
gelatine-coated  paper  having  a tendency  to  curl,  this 
being  aggravated  in  carbon  work  by  the  varying  thick- 
nesses of  the  gelatine  film,  so  that  a thin  paper  not  only 
curls  but  also  buckles.  The  coating  solution  is 

Cold  water 4 ounces 

Nelson’s  No.  1 gelatine 60  grains 

Allow  the  gelatine  to  swell  for  five  minutes  and  then 
heat  until  dissolved.  Add  a little  at  a time,  with  constant 
stirring 

Hot  water 4 drams 

Chrome  alum 12  grains 

If  the  chrome  alum  solution  is  cold  or  is  added  hastily, 
or  if  the  gelatine  solution  is  not  stirred  constantly  the 
gelatine  may  coagulate,  but  it  will  work  equally  well 
in  that  condition,  though  it  is  not  so  easy  to  use  as 
when  liquid.  The  mixed  solution  should  be  strained 
through  several  thicknesses  of  cheese-cloth  into  a 
double  boiler  and  should  be  kept  hot  while  in  use.  At 
the  end  of  the  day’s  work  the  surplus  is  thrown  away. 
The  above  quantity  will  coat  approximately  three 
22"X28"  sheets,  depending  on  the  number  of  coats 
applied.  The  gelatine  named  is  relatively  expensive, 

167 


TECHNIQUE  OF  CARBON 


but  not  actually  so,  a pound  of  it,  costing  $1.50,  having 
lasted  the  writer  over  three  years.  However,  some  of 
the  writer’s  pupils  have  used  ordinary  cooking  gelatine 
for  this  purpose,  with  perfect  success. 

It  is  convenient  to  prepare  the  paper  in  large  sheets 
and  cut  them  to  size  afterward,  but  if  this  is  not  done 
pieces  at  least  two  inches  larger  each  way  than  the 
negative  should  be  coated,  since  it  is  necessary  that 
the  transfer  paper  be  larger  than  the  tissue.  The  paper 
to  be  coated  is  pinned  by  the  four  corners  to  a hori- 
zontal board,  a small,  fine-grained  sponge  is  dipped  into 
hot  water  and  squeezed  out,  and  is  then  dipped  into 
the  gelatine  solution  and  rubbed  over  the  paper.  The 
gelatine  should  be  used  freely  and  should  be  spread 
over  the  entire  paper,  working  rapidly  and  rubbing 
until  the  paper  begins  to  show  signs  of  surface-drying, 
when  it  may  be  given  a second  application  and  be  hung 
up  to  dry.  By  the  time  the  third  sheet  has  been  coated 
the  first  will  be  ready  for  a second  treatment,  two  treat- 
ments being  sufficient  for  a smooth  paper  and  three  for 
a rough,  a very  rough,  such  as  Whatman,  requiring 
four  or  five.  The  prepared  paper  keeps  indefinitely 
without  special  precautions. 

If  the  sponge  is  cold  enough  to  chill  the  gelatine  a 
skin  will  form,  and  this  may  cause  a shiny  spot  on  the 
paper  which  will  show  in  the  finished  print.  Such  a 
spot  may  often  be  removed  by  vigorous  rubbing  with 
the  sponge  as  soon  as  it  appears,  but  if  this  does  not 
suffice  that  portion  of  the  paper  should  be  discarded. 

Should  the  gelatine  coagulate  on  addition  of  the 
chrome  alum  solution  it  may  sometimes  be  liquefied  by 
raising  the  temperature,  but  even  if  this  is  unsuccess- 

16  8 


TRANSFERRING 


ful  it  may  still  be  used,  though  it  must  then  be  rubbed 
into  the  paper  more  vigorously  than  if  liquid. 

In  an  emergency  a sheet  of  bromide  paper  which 
has  been  fixed  without  exposure  to  light,  washed  and 
hardened  may  be  used  for  transfer  paper.  To  harden, 
the  paper  should  be  given  ten  minutes  in 


Water 10  ounces 

Formaldehyde,  40  per  cent,  solution 1 ounce 


rinsed  and  dried.  Double  transfer  paper  may  also  be 
used  for  single  transfer  if  hardened  in  the  manner 
described. 

Transferring. — A pencil  mark  is  made  on  the 
back  of  the  transfer  paper  and  it  is  then  soaked  for 
half  an  hour  (longer  can  do  no  harm)  in  water  about 
65°  Fahrenheit  before  the  print  is  transferred,  and  in 
the  case  of  a very  rough  paper  it  is  well  to  give  it  five 
minutes  in  water  at  about  140°  Fahrenheit  just  before 
use.  The  print  should  be  transferred  as  soon  as  the 
exposure  is  complete,  since  bichromated  colloids  show 
a phenomenon  known  as  the  4 4 continuing  action.” 
That  is,  they  keep  on  printing  after  removal  from  light, 
and  this  action  may  result  in  a correctly  exposed  piece 
of  tissue  being  hopelessly  over-printed  four  or  five 
hours  after  being  taken  from  the  printing  frame,  even 
if  stored  in  the  dark.  The  continuing  action  may  be 
retarded  by  keeping  the  print  under  pressure,  as  in  a 
printing  frame,  or  by  storing  it  in  a platinum  tin  with 
preservative,  and  may  be  completely  arrested  by  wash- 
ing the  print  for  half  an  hour  in  cold  running  water. 

The  transfer  paper  having  been  properly  soaked 
(care  having  been  taken  to  see  that  no  air-bubbles  ad- 
hered to  it  and  that  the  coated  side  did  not  float  out 

169 


TECHNIQUE  OF  CAEBON 


of  the  water,  either  of  these  circumstances  being  likely 
to  cause  blisters  or  tearing  of  the  print)  it  is  placed  face 
down  in  a tray  of  water  at  about  65°  Fahrenheit.  The 
print  is  taken  from  the  frame  and  is  placed  face  up  in 
the  same  tray,  being  completely  covered  with  water 
and  air-bubbles  being  removed.  The  tissue  will  at  first 
tend  to  curl  up,  film  side  in,  owing  to  the  fact  that  the 
backing  absorbs  water  more  rapidly  than  the  gelatine, 
and  it  must  be  pressed  down  under  the  surface  of  the 
water.  The  tissue  will  gradually  flatten  out,  and  if 
left  for  five  or  ten  minutes  would  curl  the  other  way. 
Just  before  it  flattens  out,  however,  the  transfer  paper 
is  turned  face  up  and  the  tissue  face  down,  the  two  being 
brought  together  under  water,  film  to  film.  They  are 
lifted  out  together,  drained  for  two  or  three  seconds, 
and  laid  on  a piece  of  glass,  tissue  uppermost.  The 
tissue  is  held  in  place  with  the  fingers  of  one  hand  and 
the  squeegee  is  applied,  lightly  at  first  to  expel  any  air- 
bubbles  which  may  be  between  them  (since  these 
would  cause  blisters  in  the  finished  print)  and  then 
more  firmly,  to  expel  the  water  and  bring  the  two  films 
into  close  contact.  It  is  well  to  start  slightly  beyond 
the  middle  and  work  toward  one  end,  afterward  re- 
versing the  glass  and  working  toward  the  other  end, 
for  bubbles  thus  have  a shorter  distance  to  travel  than 
otherwise.  Squeegeeing  being  finished,  a sheet  of  blot- 
ting paper  is  laid  over  the  print  and  the  two  are  left 
under  pressure  for  half  an  hour  or  so  to  insure  firm 
cohesion  of  the  gelatine  films.  The  writer  generally 
uses  six  or  eight  old  14X17  negatives  to  furnish  the 
required  pressure,  but  in  the  case  of  a very  rough  trans- 
fer paper  it  will  be  well  to  use  half  a dozen  sheets  of 
170 


DEVELOPMENT 


blotting-paper  and  screw  the  whole  up  in  a copy -press. 

Stripping. — It  is  necessary  that  the  backing  paper 
be  stripped  off  in  order  that  the  hot  water  may  reach 
the  gelatine,  and  this  is  accomplished  in  the  following 
manner:  The  transfer  paper  with  the  adhering  tissue 

is  taken  from  under  pressure,  bending  it  as  little  as  pos- 
sible, and  is  slid,  tissue  uppermost,  into  a tray  of  water  at 
about  100°  Fahrenheit.  Air-bubbles  are  brushed  off, 
and  after  a minute  or  two  the  pigment  will  probably 
begin  to  ooze  out  from  under  the  edges  of  the  tissue. 
Should  this  not  occur  the  temperature  of  the  water 
may  be  raised  gradually  by  successive  additions  of  hot 
water  (lifting  the  print  from  the  tray  while  adding  the 
hot  water)  with  a little  wait  after  each  addition,  until 
oozing  takes  place.  After  the  pigment  has  oozed  for 
a minute  or  two  one  corner  of  the  tissue  may  be  lifted 
with  a finger-nail,  grasped  between  thumb  and  finger, 
and  stripped  off.  An  even  pull,  without  stopping,  and 
keeping  the  transfer  paper  with  the  adhering  print 
under  water,  are  generally  said  to  be  necessary,  but 
the  writer  finds  that  this  technique,  though  advisable, 
is  not  imperative.  The  backing  paper  may  be  thrown 
away  or  may  be  saved  for  the  sake  of  the  portion  of  the 
film  which  remains  on  it,  this  being  useful  for  spotting 
the  finished  print. 

Development. — No  suggestion  of  the  picture  will 
show  on  the  transfer  paper  at  first,  the  print  appearing 
simply  as  a slimy,  dark-colored  film,  with  irregular 
patches.  The  transfer  paper  is  grasped  at  one  end  and 
shaken  back  and  forth  under  the  water,  when  the  gela- 
tine and  pigment  can  be  seen  floating  off,  and  the  picture 
will  gradually  appear.  Development  should  continue 

171 


TECHNIQUE  OF  CARBON 


until  the  picture  is  slightly  lighter  than  it  should  be 
when  finished,  since  it  dries  darker  than  it  seems  when 
wet,  and  if  necessary  the  temperature  of  the  water  may 
be  raised,  since  hot  water  will  dissolve  more  of  the  gela- 
tine than  will  tepid.  The  tissue  should  be  so  printed 
that  development  may  be  completed  at  110°  Fahren- 
heit, since  a higher  temperature  than  this  is  likely  to 
cause  blisters  or  frilling,  though  the  writer  has,  in  ex- 
treme cases,  raised  the  water  to  140°  Fahrenheit. 
Such  radical  treatment,  however,  presupposes  perfect 
technique  in  preparing  the  transfer  paper  and  in  trans- 
ferring and  stripping.  Should  the  print  fail  to  develop 
satisfactorily  at  120°  Fahrenheit  a small  amount  of 
alkali,  e . g.,  stronger  ammonia,  sodium  carbonate,  or 
sodium  bicarbonate,  may  be  added  to  the  developing 
water,  perhaps  a teaspoonful  to  a quart  of  water,  but 
the  use  of  an  alkali  is  very  likely  to  cause  blisters  or 
frilling.  Care  should  be  taken  that  development  con- 
tinues until  no  irregular  dark  patches  remain  on  the 
print,  though  if  these  are  due  to  uneven  sensitizing 
rather  than  to  incomplete  development  it  will  be  im- 
possible to  remove  them.  Most  writers  recommend  the 
use  of  an  alum  bath  for  clearing  and  hardening,  but 
hardening  is  not  necessary  unless  multiple  prints  are 
to  be  made,  and  the  slight  amount  of  bichromate  re- 
maining in  the  film  will  not  be  perceptible  unless  a 
white  transfer  paper  is  used.  However,  if  it  is  desired 
to  clear  the  print,  it  may  be  given  five  minutes  in  a 
5 per  cent,  solution  of  powdered  alum,  being  afterward 
rinsed  in  three  or  four  changes  of  cold  water  and  hung 
up  to  dry.  Whether  the  clearing  bath  is  used  or  not  the 
print  should  be  rinsed. 

172 


MULTIPLE  PRINTING 


Local  Modifications. — Should  portions  of  the 
print  be  too  dark  for  the  desired  pictorial  effect  they 
may  be  raised  in  value  while  in  the  developing  water 
by  brushing  lightly  with  a tuft  of  cotton  or  a camel- 
hair  or  sable  brush,  or  by  directing  a stream  of  hot 
water  on  them,  but  this  work  should  be  done  gently 
and  cautiously  or  the  film  may  be  torn,  this  being  es- 
pecially likely  to  happen  if  development  has  been  forced 
by  means  of  an  alkali.  Local  values  may  be  raised  in 
the  dry  print  by  means  of  a hard  pencil  eraser.  Should 
it  be  desired  to  darken  an  area  this  is  best  done  on  the 
dry  print  by  softening  a little  piece  of  unexposed  tissue 
in  warm  water  and  applying  the  softened  gelatine  and 
pigment  to  the  print  with  a brush,  this  method  being 
especially  useful  for  spotting. 

Multiple  Printing. — In  multiple  printing  a single 
print  is  made  in  the  usual  manner  and  hardened,  and 
a second  or  even  third  or  fourth  print  is  superposed  on 
it.  The  second  print  may,  of  course,  be  either  in  the 
same  tissue  as  the  first  or  in  a different  one,  and  may  be 
either  lighter  or  darker  than  the  first  print,  or  of  the 
same  quality.  There  is  practically  no  limit  to  the 
number  of  printings  that  may  be  given,  the  writer 
having  superposed  five  printings  of  Ivory  Black  on  one 
of  Red  Chalk,  to  get  a special  effect.  If  different  colors 
are  used,  care  should  be  taken  to  avoid  such  as  are  com- 
plementary, since  the  combination  of  these  will  give 
black.  Thus,  an  attempt  to  print  a sunset  sky  in  red 
and  the  landscape  in  green  will  result  in  a warm  black 
sky  and  a cool  black  foreground,  unless,  of  course,  each 
portion  of  the  negative  is  shaded  while  the  other  is 
being  printed. 


173 


TECHNIQUE  OF  CARBON 


Registration. — Some  means  must  be  employed  to 
insure  that  the  outlines  of  the  second  print  coincide 
with  those  of  the  first,  and  the  simplest  method  which 
the  writer  knows  is  as  follows : A printing  frame  a size 
larger  than  the  negative,  and  fitted  with  a plate  glass, 
is  used.  A cardboard  mask  is  made,  as  shown  in  Figure 


PEHCli. 

Nr 

J 

101 

n 
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' < 

0 

1 

1 

M 

! 73"  > 

I l* 

j 0* 

i” 

. ^ 

1 

l 

s 

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X 

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1 Pfuni  -- 

_ > 

1 rOARK5 
t 1 .... 

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B 


Section  on  A~0 


Fig.  41. 

41,  the  dimensions  given  being  for  an  8X10  plate, 
since  the  worker  can  easily  modify  them  for  his  own 
size  of  negative.  The  mask  is  made  of  three  pieces  of 
cardboard  with  rectangular  openings,  as  shown,  the 
pieces  being  firmly  glued  together.  The  8J4//X103^C// 
piece  cut  from  the  third  card  should  be  saved.  This 
mask  is  placed  in  the  printing  frame,  being  supported 
174 


REGISTRATION 


by  the  plate  glass,  and  the  negative  is  laid  in  the  second 
opening,  which  should  be  of  such  size  that  the  plate 
fits  it  snugly.  Plates  vary  somewhat  in  size,  and  one 
which  is  small  enough  to  move  perceptibly  in  the  open- 
ing may  be  wedged  with  small  slivers  of  wood.  The 
sensitized  tissue  is  cut  to  fit  snugly  in  the  8J4"X103 
opening,  is  placed  in  it,  the  corresponding  piece  of  card 
is  placed  on  the  tissue  to  insure  perfect  contact  with 
the  negative,  and  the  back  of  the  frame  is  clamped  in 
place. 

The  writer’s  original  method  called  for  a two-ply 
mask,  pencil-marks  serving  as  guides  for  registration, 
and  the  addition  of  the  third  piece,  which  holds  the 
tissue,  was  the  suggestion  of  one  of  the  writer’s  pupils. 
Obviously,  however  many  prints  are  made  in  this  man- 
ner, the  outlines  of  the  negative  and  the  edges  of  the 
tissue  will  always  be  in  the  same  relative  position,  and 
if  steps  are  taken  to  insure  placing  successive  pieces 
of  tissue  in  the  same  relative  positions  on  the  transfer 
paper,  the  printings  must  register.  Guide  marks  are 
made  on  the  transfer  paper  with  a fine-pointed  B or 
2B  pencil,  as  shown  in  Figure  42,  this  being  done  after 
the  tissue  has  been  squeegeed  to  the  transfer  paper, 
and  either  before  putting  the  two  under  pressure  or 
just  before  stripping.  Stripping  and  development  pro- 
ceed in  the  usual  manner,  but  the  finished  print  should 
be  hardened  before  putting  to  dry,  hardening  being 
advisable  though  not  imperative.  Hardening  is  best 
accomplished  by  soaking  the  print  for  ten  minutes  in 


Water 10  ounces 

Formaldehyde,  40  per  cent,  solution 1 ounce 


A 10  per  cent,  chrome  alum  solution  may  be  used,  but 

175 


TECHNIQUE  OF  CARBON 


the  formaldehyde  is  preferable,  since  formaldehyde  is 
an  aqueous  solution  of  a gas,  which  is  driven  off  by 
drying,  whereas  chrome  alum,  unless  thoroughly 
washed  out  of  the  film,  may  cause  reticulation  of  the 
second  print.  The  second  and  subsequent  prints  are 
registered  with  the  negative  exactly  as  the  first,  and  in 
applying  them  to  the  first  print  this  is  soaked  just  like 
a new  piece  of  transfer  paper,  the  corners  of  the  second 


print  being  made  to  coincide  with  the  pencil  marks 
before  squeegeeing.  It  may  be  that  the  second  print 
will  swell  to  a size  different  from  that  of  the  first,  or 
that  the  paper  carrying  the  first  print  will  not  expand 
to  its  original  size,  and  in  this  case  the  only  thing  to  do 
is  to  register  as  nearly  as  possible,  since  the  variation 
is  not  likely  to  be  of  importance  in  pictorial  work. 
Stripping  and  development  of  the  second  print  pro- 
ceed as  in  the  case  of  the  first. 

Failures. — It  is  not  possible  to  give,  in  a book  the 

176 


FAILURES 


size  of  the  present  one,  a complete  list  of  all  the  causes 
of  failure  that  may  occur  in  carbon  work,  since  such  a 
list  would  occupy  too  much  space;  but  this  fact  need 
not  deter  the  amateur  from  taking  up  carbon  printing, 
many  of  the  faults  in  question  being  unlikely  to  occur. 
Still,  a few  of  the  more  usual  ones  may  be  mentioned. 

Tissue  which  has  dried  too  slowly  or  has  been  kept 
too  long  after  drying  will  give  degraded  lights,  and  may 
refuse  to  adhere  to  the  transfer  paper;  failure  to  adhere, 
either  all  over  or  in  spots,  being  also  due  at  times  to 
insufficient  soaking  of  the  transfer  paper  or  excessive 
soaking  of  the  tissue  before  squeegeeing,  to  insufficient 
pressure,  or  to  an  attempt  to  transfer  to  the  uncoated 
side  of  the  transfer  paper. 

Air-bubbles  on  either  tissue  or  transfer  paper,  at 
any  stage  of  the  work,  may  cause  blisters,  and  these 
may  also  result  from  the  use  of  water  at  too  high  a tem- 
perature or  of  alkali. 

Frilling  or  tearing  may  be  caused  by  the  use  of  a 
tissue  with  old  edges,  by  undue  haste  or  roughness  in 
stripping,  by  serious  over-printing,  or  by  the  fact  of  the 
tissue  overlapping  the  edge  of  the  transfer  paper. 

Using  the  sensitizer  below  60°  Fahrenheit  may 
cause  reticulation  of  the  film  and  if  the  sensitizer  is 
above  75°  Fahrenheit  the  gelatine  may  be  softened, 
even,  in  extreme  cases,  melting.  Hence,  if  the  room 
temperature  is  80°  Fahrenheit  or  more,  it  is  advisable 
to  chill  the  sensitizer  and  the  ferrotype  plate. 

Grease  may  cause  blank  spots  on  the  print,  or  even 
blisters,  the  chief  danger  from  this  cause  lying  in  finger 
marks,  this  circumstance  furnishing  an  additional 

reason  for  using  rubber  gloves. 

12 


177 


TECHNIQUE  OF  CARBON 


General  Remarks. — It  may  be  thought,  from  the 
long  and  apparently  complicated  description  of  the 
process,  that  carbon  printing  is  difficult,  but  this  is  by 
no  means  the  case.  The  writer  has  heard  of  an  expert 
carbon  printer  who,  starting  with  the  sensitized  tissue, 
finished  two  hundred  prints  in  a day,  this  being  far  in 
excess  of  what  any  pictorial  worker  will  wish  to  make. 

If  it  is  desired  to  have  the  print  the  right  way 
around,  and  to  have  precise  definition,  double  transfer 
may  be  resorted  to,  in  which  the  print  is  first  transferred 
to  a temporary  support,  where  it  is  developed,  and  there 
retransferred  to  a final  support.  The  writer,  however, 
has  never  found  this  method  to  possess  any  advantages 
for  pictorial  work,  and  it  unquestionably  has  several 
disadvantages,  since  it  adds  an  extra  process — the  most 
delicate  of  all — and  limits  the  possibilities  in  the  matter 
of  texture,  the  only  surface  possible  in  double  transfer 
being  a smooth  one.  Of  course  if  an  enlarged  negative 
is  to  be  used  it  may  be  reversed  at  the  time  of  enlarging, 
but  the  diffusion  resulting  from  printing  from  the  back 
of  the  plate  is  not  likely  to  be  in  excess  of  that  desired 
by  the  pictorial  worker. 

Speed  and  Scale  of  Carbon  Tissues. — The  vari- 
ous carbon  tissues  render  widely  different  scales  of 
gradation  and  print  with  different  speeds.  The  writer 
has  never  seen  any  definite  information  bearing  on  these 
points,  and  feels  that  something  of  the  sort  would  be 
valuable  to  pictorial  workers,  both  in  enabling  them 
to  adjust  the  printing  time  with,  in  consequence,  a 
possible  saving  of  material,  and  also  in  making  it  pos- 
sible for  them  to  select  the  carbon  tissue  which  will 
best  render  the  negative  in  question  or  to  make  the 

178 


CARBON  TISSUES 


negative  to  suit  the  tissue  to  be  used.  Of  course,  the 
selection  of  the  tissue  does  not  depend  merely  on  the 
scale  of  the  negative,  since  the  color  to  be  used  for 
printing  is  of  importance,  but  it  often  happens  that 
there  is  a possibility  of  choice  among  several  tissues, 
for  there  are  five  different  blacks  and  there  are  also 
other  tissues  of  very  similar  character. 

The  experimental  work  involved  in  making  up  the 
table  given  below  was  done  by  one  of  the  writer’s 
pupils,  Mr.  W.  R.  Latimer,  class  of  1915,  and  was 
carried  out  in  the  following  manner:  A photometer  of 
forty  steps  was  first  made  by  gluing  as  many  pieces 
of  tracing  paper  to  a glass  plate,  each  piece  except  the 
first  having  in  it  an  opening  slightly  larger  than  the 
preceding  one,  that  is,  the  first  piece  was  entire,  the 
second  piece  had  an  opening  J/£"X1",  the  third  an 
opening  1"  square,  the  fourth  an  opening  1J^"X1" 
and  so  on.  Thus  it  will  be  seen  that  forty  steps  differ- 
ing from  one  another  by  slight  gradations  resulted, 
and  the  different  tissues  having  been  sensitized  and 
dried  as  nearly  as  possible  in  uniform  conditions  were 
printed  in  this  photometer  exactly  as  though  the  latter 
were  an  ordinary  negative,  a constant  light  (mercury 
vapor  arc)  being  used.  The  printing  time  in  each  case 
was  adjusted  so  that  the  lower  gradations  of  the  pho- 
tometer were  blocked  up,  and  in  no  case  would  the  tis- 
sue register  the  full  number  of  steps.  The  steps  were  of 
course  numbered  in  sequence,  the  thinnest  being  1 and 
the  densest  being  40.  Development  in  each  case  was 
in  water  at  precisely  112°  Fahrenheit.  The  scale  of  the 
tissue  was  determined  by  the  number  of  tints  visible 
in  the  finished  print,  the  lowest  being  the  first  to  block 

179 


TECHNIQUE  OF  CARBON 


up  and  the  highest  the  last  one  which  showed  a distinct 
tint  on  the  paper;  that  is,  if  3 and  4 showed  no  differ- 
entiation but  4 and  5 did,  four  was  considered  to  be  the 
extreme  dark  of  the  tissue.  This  table  does  not  show 
any  relation  between  the  printing  speed  of  the  tissue 
and  the  printing  speed  of  P.  O.  P.,  since,  as  noted  above, 
the  latter  varies  considerably  in  speed.  Ivory  Black 
was  found  to  be  the  most  rapid  printing  tissue,  and  the 
speeds  of  the  other  tissues  are  indicated  in  relation  to 
this.  That  is,  if  a certain  negative  requires  one  minute 
exposure  to  print  in  Ivory  Black,  it  will  need  one  and 
one-quarter  minutes  to  print  in  Warm  Black.  These 
speeds  are  approximate  only. 


Tissue. 

Relative  Speed. 

Scale. 

Ivory  Black 

.1 

15 

Blue  Black 

1 

15 

Warm  Black 

IK 

15 

Neutral  Ink 

• iK 

13 

Brownish  Black 

23^ 

16 

Platino  Black 

IK 

16 

Standard  Brown 

2 

16 

Vandyke  Brown. . 

IK 

18 

Portrait  Brown 

2K 

19 

Ruby  Brown 

iK 

17 

Chocolate  Brown 

3 

15 

Cold  Bistre 

iK 

18 

Green  Sepia 

. iK 

19 

Rembrandt  Sepia 

.....iK 

18 

Cool  Sepia 

2K 

16 

Sepia 

....iK 

17 

Turner  Sepia 

..2 

19 

Italian  Green 

iK 

18 

Gray  Green 

2K 

15 

Terra  Cotta 

3K 

18 

Bright  Mauve 

IK 

13 

CHAPTER  XII 

TECHNIQUE  OF  GUM 

Theory. — The  theory  of  gum  printing  is  the  same 
as  that  of  carbon  in  so  far  as  it  depends  on  the  insolu- 
bilization of  a bichromate-sensitized,  pigmented  colloid 
film  by  the  action  of  light,  but  varies  from  it  in  one 
important  respect.  In  both  cases  the  image  consists 
of  varying  thicknesses  of  pigment-bearing  colloid,  but 
in  gum  work  the  variations  of  thickness  are  due  to  the 
fact  that  the  paper  support  is  rough,  so  that,  if  the  film 
has  approximately  a uniform  surface,  the  insoluble  col- 
loid extends  varying  distances  down  the  sides  of  the 
little  projections  on  the  surface  of  the  paper,  the  vary- 
ing thickness  of  the  film  resulting  from  this  irregularity 
in  the  surface.  An  interesting  consequence  follows 
from  this,  namely,  that  if  a smooth  gum  coating  is 
spread  on  a perfectly  smooth  surface,  such  as  glass,  no 
half-tones  can  be  obtained  on  printing,  a silhouette 
resulting,  but  if  the  gum  coating  is  stippled  a print  with 
half-tones  may  be  made,  though  the  scale  will  be  limited. 
It  follows,  also,  that  a rough  paper  will  give  a longer 
scale  of  gradation  than  a smooth,  this  fact  being  of 
importance  to  the  gum  printer. 

In  practice  gum  differs  from  carbon  in  that  the  col- 
loid used  is  gum  arabic  instead  of  gelatine,  that  cold 
water  instead  of  hot  is  (normally)  used  for  develop- 
ment, that  development  takes  place  not  from  the  back  of 
the  film  but  from  the  front,  the  soluble  colloid  seeping 
out  through  the  pores  of  the  overlying  insoluble  layer, 

181 


TECHNIQUE  OF  GUM 


and  that  the  paper  cannot  be  bought  ready  prepared, 
but  must  be  coated  by  the  user. 

Materials  Required. — The  materials  necessary 
for  gum  work  are  paper,  gum  arabic,  a bichromate 
salt,  pigment,  and  two  brushes,  one  for  spreading  and 
one  for  blending.  These  will  be  considered  in  the  order 
given. 

Many  different  papers  are  available,  the  two  requi- 
sites being  that  the  stock  shall  be  such  as  to  stand  pro- 
longed soaking  in  water,  and  that  it  shall  be  fairly  well 
sized.  Any  good  drawing  or  charcoal  paper,  such  as 
Strathmore,  Lalanne,  or  Whatman,  may  be  used,  but 
some  will  need  resizing  if  multiple  prints  are  to  be 
made. 

It  is  best  to  procure  the  highest  grade  of  gum  arabic 
and  to  obtain  it  in  the  form  of  lumps  rather  than  pow- 
dered. It  is  most  convenient  to  make  up  a stock  solu- 
tion of  the  gum  as  follows:  Procure  a large-mouthed 
bottle  and  tie  two  thicknesses  of  cheese-cloth  over  the 
top,  so  that  the  cloth  hangs  down  in  the  form  of  a bag. 
Into  this  bag  put  £200  grains  of  gum  arabic  and  pour 
through  it  12  ounces  of  water  in  which  have  been  dis- 
solved 30  grains  of  mercuric  chloride.  See  that  the 
gum  hangs  below  the  surface  of  the  water,  and  allow 
it  to  stand,  occasionally  stirring  the  gum,  until  solu- 
tion has  taken  place,  two  or  three  days  being  required. 
The  function  of  the  mercuric  chloride  is  to  act  as  a 
preservative,  for,  although  a sour  gum  solution  works 
quite  as  well  as  a fresh,  it  works  differently,  and  will 
not  be  dependable  for  constant  results.  This  gum  solu- 
tion will  keep  for  months. 

The  sensitizer  may  be  the  bichromate  of  either 

182 


MATERIALS  REQUIRED 


potassium,  ammonium,  or  sodium,  the  first  being 
usually  recommended.  The  writer  prefers  the  last- 
named,  since  it  may  be  made  up  in  a much  more  con- 
centrated solution,  giving  a quicker  printing  film.  The 
cost  per  pound  of  the  salt  is  practically  the  same.  If 
the  potassium  salt  is  used  the  sensitizer  is 

Water,  hot j 30  ounces 

Potassium  bichromate 1440  grains 

If  sodium  bichromate  is  used  the  formula  is 

Water,  hot 32  ounces 

Sodium  bichromate 2 pounds 

The  sensitizer  keeps  indefinitely. 

The  pigments  may  either  be  dry  powders  or  in 
water-color  tubes,  the  writer  preferring  the  latter,  since 
the  dry  powders  require  grinding,  this  being  a laborious 
and  dirty  process.  Oil  colors  cannot  be  used  success- 
fully. The  water-colors  may  be  those  of  any  good 
maker,  such  as  Talens  & Son,  Winsor  & Newton,  or 
Devoe,  but  it  is  best  to  adhere  to  those  of  one  maker, 
since  the  different  makes  vary  somewhat. 

The  fundamental  color  most  used  is  black,  and  posi- 
tive colors  such  as  red,  green,  and  blue  are,  generally 
speaking,  to  be  avoided  for  esthetic  reasons.  It  is, 
however,  desirable  at  times  to  modify  the  black  some- 
what in  order  to  obtain  cold  or  warm  blacks  or  browns, 
and  the  following  pigments  will  be  found  useful : 

Lamp  Black,  a strong  color  having  a slight  greenish 
tinge. 

Ivory  Black,  a much  weaker  color,  but  pure. 

Rembrandt  Black,  a strong  pure  color  manufactured 
by  Talens  & Son. 

Burnt  Umber,  a weak  brown,  very  useful  for  modi- 
fying blacks. 


183 


TECHNIQUE  OF  GUM 

Burnt  Sienna,  similar  to  Burnt  Umber,  but  reddish 
in  hue. 

Prussian  Blue,  a strong,  slightly  greenish  color. 

Cobalt  Blue,  weaker  than  Prussian  blue,  but  pure. 

Cadmium  Orange,  a strong  pure  color. 

Some  workers  advise  other  colors  in  addition  to 
those  enumerated,  but  the  writer  finds  that  the  ones 
named  will  do  practically  everything  that  is  desired 
except  in  very  special  circumstances. 

The  spreading  brush  should  be  of  moderately  stiff 
bristles,  though  if  it  is  too  stiff  the  paper  may  be  in- 
jured. A good  width  of  brush  for  any  size  of  print  up 
to  20"X24"  is  three  inches.  The  blending  brush  is 
the  type  known  as  a “flat  badger  blender,”  and  should 
preferably  be  about  four  inches  wide,  since  a smaller 
one  will  not  work  satisfactorily  with  large  prints.  After 
some  skill  has  been  acquired  it  will  be  found  possible 
to  blend  perfectly  on  rough  papers  with  the  spreader, 
but  the  blender  is  always  useful.  The  use  of  these 
brushes  is  not,  however,  imperative,  since  practice  will 
enable  the  worker  to  spread  and  blend  with  any  kind 
of  brush  that  is  not  too  stiff. 

Sizing. — With  good  drawing  papers  it  will  not  be 
necessary  to  size  even  if  multiple  prints  are  to  be  made, 
but  some  stocks  are  so  porous  that  unless  sized  they 
will  absorb  the  pigment  unduly.  The  size  may  be 
either  temporary  or  permanent,  the  former  being  the 
easier  to  apply  if  only  single  prints  are  to  be  made,  but 
it  possesses  the  disadvantage  that  it  must  be  applied 
before  each  coating  of  the  paper,  thus  introducing  addi- 
tional operations,  whereas  if  the  paper  is  permanently 
sized  one  application  is  sufficient,  no  matter  how  many 

184 


THE  COATING  MIXTURE 


printings  are  given.  The  temporary  sizing  consists  of 
a moderately  thick  boiled  starch  paste  which  is  applied 
to  the  paper  by  means  of  a damp  sponge  and  well 
rubbed  in.  For  permanent  sizing  the  formula  is  the 
same  as  that  given  in  the  preceding  chapter  for  carbon 
transfer  paper,  one  application,  or  at  most  two,  being 
sufficient  to  produce  the  desired  result. 

The  Coating  Mixture. — The  coating  mixture 
consists  of  gum  solution,  sensitizer  and  pigment,  and 
is  capable  of  infinite  variations,  though  a few  general 
rules  may  be  given: 

1.  Increasing  the  proportion  of  gum  increases  con- 
trast. 

2.  Increasing  the  amount  of  size  in  the  paper  in- 
creases contrast. 

3.  Increasing  the  proportion  of  pigment  decreases 
contrast  and  gives  a longer  scale  of  gradation. 

4.  Excess  of  pigment  will  stain  the  paper  and  pro- 
duce degraded  lights. 

5.  Increasing  the  proportion  of  sensitizer  renders 
the  mixture  easier  to  spread  and  blend,  but  gives  a 
thinner  film. 

For  every  paper  and  every  pigment  there  is  a 
certain  relationship  between  the  amount  of  gum  and 
the  amount  of  pigment  which  will  give  the  longest  scale 
of  gradations  without  staining  the  paper.  This  rela- 
tionship is  of  great  importance  and  may  be  determined 
as  follows.  Take  a definite  amount  of  the  pigment 
(say  one  inch  squeezed  from  a water  color  tube)  and  to 
it  add  dram  of  the  gum  solution.  Dipping  a fine 
brush  into  this  mixture,  which  should  have  been 
thoroughly  stirred,  make  a mark  on  a piece  of  the 

185 


TECHNIQUE  OF  GUM 


paper  under  investigation.  Opposite  this  mark  write  in 
pencil  “1  inch  to  3^2  dram”;  add  another  Yl  dram  of 
the  gum  solution,  stir  thoroughly  and  make  another 
mark  labeling  this  “1  inch  to  1 dram”;  add  another  Y 
dram  of  the  gum  and  proceed  in  the  same  manner, 
continuing  the  additions  of  gum  until  the  proportion 
of  pigment  to  gum  is  about  1 inch  to  2 ounces.  It  will 
be  observed  that  no  sensitizer  is  used  in  this  test. 
Allow  the  gum  to  dry  thoroughly  on  the  paper  and 
then  float  the  latter,  gum  side  down,  for  one  hour  in 
water  at  room  temperature,  without  agitation.  At 
the  end  of  this  time  examine  the  paper  and  it  will  be 
found  that  some  of  the  marks  have  disappeared  en- 
tirely, some  are  faintly  visible  and  others  are  very 
distinct;  thus  it  may  be  found  that  the  highest  mark 
is  opposite  the  pencil  label  44 1 inch  to  8 drams,”  then 
if  the  gum  pigment  mixture  be  made  up  in  the  propor- 
tions of  1 inch  of  pigment  to  8 drams  of  gum  the 
lights  in  the  resulting  print  will  be  faintly  degraded, 
the  amount  of  degradation  being  probably  so  slight 
as  to  be  immaterial  in  single  printing,  though  it  will  of 
course  become  apparent  if  multiple  prints  are  made, 
and  in  this  case  it  will  be  necessary  to  take  SY  drams 
of  gum  to  1 inch  of  pigment  if  clear  lights  are  desired. 
A note  having  been  made  of  the  proper  proportion  of 
gum  to  pigment  necessary  for  obtaining  clear  lights  in 
automatic  development,  a soft  camel-hair  or  sable 
brush  may  be  rubbed  over  the  test  paper,  when  it  will 
be  found  that  still  others  of  the  marks  disappear,  the 
highest  remaining  after  this  treatment  being  perhaps 
opposite  the  label  44 1 inch  to  4^  drams.”  This  indi- 
cates that  if  5 drams  of  gum  be  used  to  1 inch  of  pig- 
186 


THE  COATING  MIXTURE 


ment,  clear  lights  will  be  obtained  by  the  use  of  a 
brush  or  atomizer  on  the  print  during  development. 
This  test  must  be  made  for  each  paper  and  each  pig- 
ment to  be  used,  since  some  papers  stain  more  readily 
than  others  and  some  pigments  have  far  greater 
tendency  to  stain  than  is  the  case  with  others.  If  two 
pigments  are  to  be  mixed  the  amount  of  gum  to  be 
used  follows  naturally  from  the  above  test,  thus  if  we 
say  that  it  is  necessary  to  use  4 drams  of  gum  per  inch 
of  Ivory  Black  and  6 drams  per  inch  of  Burnt  Umber, 
then  if  1 inch  of  Ivory  Black  and  1 inch  of  Burnt  Umber 
are  mixed  in  order  to  obtain  a brown  it  will  of  course 
be  necessary  to  use  10  drams  of  gum.  In  general  the 
transparent  pigments  such  as  Burnt  Umber  and  Burnt 
Sienna  have  a greater  tendency  to  stain  than  the  more 
opaque  ones  such  as  the  blacks. 

Inasmuch  as  the  proportions  of  the  coating  mixture 
vary  with  the  pigment  used,  with  the  paper  on  which 
the  print  is  to  be  made,  and  with  the  result  desired, 
every  worker  must  determine  for  himself  what  mixture 
he  will  use  in  a given  case,  and  although  numerous 
formulse  could  be  given,  to  do  so  would  occupy  an 
excessive  amount  of  space  and  would  serve  no  useful 
purpose,  since  it  is  obviously  impossible  to  cover  all 
conditions.  Therefore  but  one  formula  for  the  coating 
mixture  will  be  given  and  the  worker  will  be  left  to 
make  his  own  application  of  the  fundamental  principles 
stated  above.  This  formula  the  writer  has  found  to 
work  satisfactorily  with  Strathmore  Detail  paper: 


Gum  solution 6 drams 

Sensitizer 11  drams 

Rembrandt  Black 1 inch 

Burnt  Umber 1 inch 


187 


TECHNIQUE  OF  GUM 

This  gives  a good  warm  brown  and  does  not  stain  the 
paper. 

Coating  the  Paper. — The  paper  to  be  coated  is 
pinned  by  the  four  corners  to  a smooth  horizontal 
board,  the  pigment  is  put  into  a mortar  or  saucer  and 
the  gum  solution  added  a little  at  a time,  rubbing 
thoroughly  with  the  pestle  or  with  the  spreading  brush 
until  the  gum  and  pigment  have  been  completely 
mixed.  The  sensitizer  is  then  added  and  the  whole 
thoroughly  stirred.  The  bristle  brush  is  dipped  into 
the  mixture  and  is  brushed  rapidly  back  and  forth 
across  the  paper,  which,  as  in  the  case  of  platinum 
sensitizing,  should  be  rather  larger  than  the  print  is  to 
be.  It  will  probably  be  found  that  the  paper  will 
stretch  when  the  mixture  is  applied  to  it  and  the  slack 
should  be  taken  up  by  shifting  the  pins,  glass  push- 
pins being  recommended,  since  they  are  easier  to 
manipulate  than  the  ordinary  type.  The  mixture  hav- 
ing been  spread  as  evenly  as  possible  with  the  coating 
brush,  the  blender  is  then  taken  up  and  the  streaks  left 
in  coating  are  smoothed  out  with  it.  Experience  only 
can  indicate  the  amount  of  mixture  to  be  applied  to 
the  paper,  for  if  too  little  is  put  on  it  will  be  impossible 
to  cover  the  paper  completely,  whereas  if  too  much 
is  applied  the  film  will  be  so  thick  that  it  will  flake  in 
developing.  The  rougher  the  paper  the  more  of  the 
coating  mixture  it  will  take,  but  no  definite  indication 
can  be  given.  The  use  of  the  blender  requires  con- 
siderable manipulative  skill,  which  also  can  be  obtained 
only  through  experience.  The  blender  should  be  held 
as  nearly  vertical  as  possible  and  should  not  press 
heavily  on  the  paper,  only  the  tips  of  the  hairs  touch - 

188 


COATING  THE  PAPER 


ing,  and  should  be  moved  rapidly  up  and  down  and 
crosswise  of  the  sheet  until  the  coating  is  uniform  and 
for  a little  time  thereafter.  If  blending  is  stopped  too 
soon  the  mixture  will  run  together  in  little  puddles 
and  will  give  spotty  prints,  whereas  if  it  is  continued 
too  long,  that  is  after  the  mixture  grows  tacky,  the 
hairs  of  the  brush  will  cause  streaks  which  may  show 
in  the  finished  print.  A slight  streakiness  will  disap- 
pear during  the  operations  of  drying  the  coated  paper 
and  developing  the  print,  and  it  is  sometimes  possible 
to  remove  brush  marks  by  stippling  the  print  all  over 
with  the  blender,  though  this  gives  an  entirely  dif- 
ferent texture  in  the  final  result.  Generally  speaking, 
blending  should  not  occupy  more  than  about  thirty 
seconds,  though  with  rough  paper  it  may  take  longer. 

The  operations  of  preparing  and  applying  the  coat- 
ing mixture  may  be  carried  out  in  an  ordinary  room 
since,  as  in  the  case  of  carbon,  the  paper  is  not  sensi- 
tive until  dry,  but  drying  should  take  place  in  the  dark 
and  in  ordinary  circumstances  will  not  occupy  over  an 
hour.  If  several  sheets  of  paper  have  been  coated  the 
blender  will  be  clogged  with  the  mixture  and  will  refuse 
to  work  properly,  when  it  may  be  cleaned  by  rinsing 
under  the  faucet  and  spinning  the  handle  between 
the  hands. 

If  the  gum-pigment  mixture  is  too  thick  it  will  set 
before  it  can  be  blended  satisfactorily,  whereas  if  it  is 
too  thin  it  will  take  an  excessively  long  time  to  blend. 

Some  papers,  especially  thin  ones,  buckle  so  when 
wet  that  it  will  be  impossible  to  blend  the  mixture 
properly.  If  this  is  found  to  be  the  case  the  trouble 
may  be  avoided  by  soaking  the  paper  until  it  is  limp, 

189 


TECHNIQUE  OF  GUM 


surface-drying  between  blotters  and  coating  while  it 
is  still  damp.  However,  if  this  is  done  there  will  be  a 
greater  tendency  for  the  pigment  to  stain  the  paper 
than  if  the  latter  is  coated  dry,  and  allowance  must  be 
made  for  this  fact  when  preparing  the  coating  mixture. 

Printing. — It  is  quite  as  impossible  to  give  definite 
rules  for  printing  as  it  is  to  give  definite  rules  for  the 
coating  mixture,  since  the  printing  speed  of  the  paper 
depends  on  the  proportion  of  gum  and  sensitizer,  on 
the  proportion  and  color  of  pigment,  and  of  course  on 
the  quality  of  the  light  and  of  the  negative.  Obviously 
the  greater  the  proportion  of  sensitizer  and  the  less  the 
proportion  of  pigment  the  more  rapid  the  paper  will 
be,  but  the  color  of  the  pigment  also  exerts  a marked 
influence,  pigments  of  non-actinic  color  of  course  print- 
ing more  slowly  than  the  blues  and  greens.  Generally 
speaking,  blue  will  print  most  rapidly,  black  next  and 
then  brown  and  red  in  the  order  given.  With  the 
coating  mixture  given  above  the  printing  time  will  be 
roughly  that  of  platinum,  provided  the  potassium  bi- 
chromate sensitizer  is  employed,  though  if  the  sodium 
bichromate  sensitizer  is  used  the  printing  time  will  be 
about  one-fourth  of  this.  It  is  possible  to  make  an 
actinometer  which  will  enable  the  worker  to  print 
accurately,  but  the  writer  prefers  to  rely  on  experience 
and  on  the  use  of  test  slips,  printing  by  time,  since  this 
is  generally  easier  than  the  other  method. 

Development. — The  print  should  be  developed  as 
soon  as  taken  from  the  frame,  for  the  continuing  action 
of  light  is  the  same  with  gum  as  with  carbon,  and  to 
effect  this  the  print  is  slid  into  a tray  of  water  at  room 
temperature,  allowed  to  remain  until  limp,  the  water 

190 


THE  DRIVING  WIND 
BY  PAUL  L.  ANDERSON 
From  a Gum-platinum  Print 


DEVELOPMENT 

being  changed  two  or  three  times  if  convenient,  and  is 
then  turned  face  down,  care  being  taken  to  see  that  no 
air-bubbles  adhere  to  either  the  front  or  back,  since  if 
this  occurs  dark  spots  are  likely  to  result  in  the  finished 
picture.  The  proper  way  to  avoid  air-bubbles  in  turn- 
ing the  print  face  down  is  to  lift  it  by  both  ends,  bend- 
ing it  in  the  form  of  a “U”  and  to  lower  it  gently  until 
the  middle  touches  the  water.  The  ends  can  then  be 
lowered  gradually  and  any  loose  air-bubbles  will  run 
out  from  under  the  paper  as  this  is  brought  down  to  the 
surface  of  the  water.  Development  may  be  either 
automatic  or  forced,  the  former  consisting  simply  in 
allowing  the  print  to  remain  face  down  in  the  tray 
until  all  of  the  soluble  gum  has  floated  off,  raising  the 
temperature  of  the  water  if  this  proves  necessary. 
The  high-lights  of  the  picture  or  the  edges  where  the 
print  is  protected  from  light  by  the  rebate  of  the 
printing  frame  should  appear  in  ten  minutes  or  less  and 
development  should  be  complete  in  from  one-half  to 
one  hour.  If  less  time  than  this  is  required  for  the 
picture  to  appear  as  it  should  when  finished,  the  print 
is  probably  under-exposed  and  the  gum  and  pigment 
will  run  in  drying.  If  development  requires  more 
than  one  hour  for  completion  over-exposure  is  indicated, 
and  this  may  be  treated  either  by  allowing  the  print 
to  remain  in  the  water  until  it  is  fully  developed,  the 
writer  having  at  times  allowed  prints  to  develop  for 
forty-eight  hours,  or  if  the  exposure  has  been  too  great 
for  this  by  raising  the  temperature  of  the  water  and  in 
extreme  cases  by  adding  a slight  amount  of  alkali  to 
the  developing  water,  as  indicated  in  the  chapter  on 
carbon  printing.  The  completion  of  development  may 

191 


TECHNIQUE  OF  GUM 


be  determined  by  raising  the  print  from  the  tray  and 
allowing  the  water  to  drain  from  one  comer  back  into 
the  tray — which  should  be  porcelain  or  porcelain-lined 
— when  a stream  of  pigment  will  be  seen  running  into 
the  tray  if  development  is  not  complete.  When  all  the 
soluble  pigment  has  been  washed  off  the  water  drain- 
ing from  the  print  will  not  be  discolored,  but  develop- 
ment may  safely  be  arrested  slightly  before  this  point 
is  reached.  That  is,  if  only  a comparatively  slight 
discoloration  of  the  water  is  observed  there  is  no 
danger  of  the  gum  and  pigment  running  provided  the 
print  is  hung  up  to  dry,  which  should  nearly  always 
be  done.  If  the  print  is  laid  in  a horizontal  position 
a film  of  water  will  remain  on  it  much  longer  than  if  it 
is  vertical  and  this  film  will  tend  to  soften  the  gum  still 
further  and  to  cause  running.  A very  beautiful  effect 
may  be  obtained  in  this  manner  if  the  running  is  but 
slight,  though  to  secure  this  effect  at  its  best  the  exposure 
must  be  absolutely  correct  and  development  must  be 
arrested  at  precisely  the  proper  time. 

The  gum  adheres  to  the  paper  but  slightly  when 
water-soaked,  and  for  this  reason  values  may  be  light- 
ened to  almost  an  unlimited  extent  during  development. 
To  effect  this  lightening  various  methods  may  be  em- 
ployed, these  being  arranged  below  in  the  order  of  their 
vigor,  the  first  producing  the  least  effort.  The  print 
should  have  been  soaked  for  at  least  ten  minutes  before 
starting  forced  development,  and  the  effect  is  greater 
if  soaking  has  been  longer  than  this. 

1.  The  print  is  supported  at  an  angle  on  a sheet 
of  glass  and  a stream  of  water  is  allowed  to  flow  gently 
over  it  from  a hose  or  graduate. 

192 


DEVELOPMENT 


2.  The  sheet  of  glass  carrying  the  print  is  set 
nearly  vertical  and  the  print  is  sprayed  with  cold  water 
from  an  atomizer,  the  most  desirable  being  the  kind 
designed  to  spray  heavy  liquids,  such  as  albolene. 
The  effect  of  using  the  atomizer  is  more  vigorous  and 
more  concentrated  when  the  nozzle  approaches  close 
to  the  print,  diminishing  in  power  and  spreading 
over  a larger  area  as  the  nozzle  recedes  from  the 
paper. 

3.  The  print  being  nearly  horizontal,  a succession 
of  drops  of  water  is  allowed  to  fall  on  it  from  a slight 
elevation,  either  from  a hose  or  from  a graduate. 

4.  The  print  is  lightly  brushed  while  under  water 
with  a soft  camel-hair  brush. 

5.  The  camel-hair  brush  is  used  while  the  print  is 
out  of  water. 

6.  The  end  of  a hose  which  is  attached  to  the 
faucet  is  pinched  up  and  a fine  stream  of  water  is 
directed  against  the  print,  the  latter  being  supported 
on  a sheet  of  glass. 

7.  A stiff  bristle  brush  is  used  on  the  film. 

Whatever  method  is  used  the  print  should  be  rinsed 

in  clean  water  before  being  hung  up  to  dry. 

It  is  difficult  to  apply  any  of  these  methods  so  as 
to  produce  a decided  change  in  values  without  interfer- 
ing with  the  photographic  quality  of  the  print  by  intro- 
ducing brush  marks  or  other  indications  of  manipulation, 
and  for  this  reason  automatic  development  is  advised 
whenever  it  will  produce  the  desired  result,  since  an 
evident  mixture  of  mediums,  that  is,  photography  and 
hand-work,  is  a violation  of  unity  and  as  such  is  to  be 
condemned  from  an  artistic  point  of  view.  To  be  sure,  it 

13  193 


TECHNIQUE  OF  GUM 


is  possible  to  modify  values,  as  has  been  said,  to  almost 
an  unlimited  extent,  and  some;  workers  use  the  gum 
process  with  this  end  in  view,  producing  effects  which 
bear  some  resemblance  to  a charcoal  sketch  or  a pastel 
drawing,  but  this  practice  cannot  be  too  severely 
condemned  on  artistic  grounds. 

An  interesting  comparison  is  observable  between 
different  schools  of  gum  workers,  this  comparison  being 
especially  noticeable  as  regards  the  French  and  the 
German  schools,  the  former  generally  working  with 
one  gum  coating  and  with  moderate  size  negatives, 
and  developing  very  largely  by  means  of  a brush,  so 
that  the  result  has  much  the  character  of  a charcoal 
or  chalk  drawing.  The  Germans  and  Austrians,  on  the 
other  hand,  work  in  large  sizes  and  develop  auto- 
matically, giving  several  printings  to  a sheet  of  paper, 
the  evident  intention  being  to  produce  mural  prints 
rather  than  portfolio  pictures  and  to  vie  directly  with 
oil  painting  in  effect.  American  workers  do  compara- 
tively little  gum  work,  their  use  of  the  medium  being 
chiefly  for  addition  to  platinum,  and  English  workers 
tend  more  to  moderate  size  negatives  automatically 
developed. 

Multiple  Printing— Gum  being  a short  scale 
process,  it  is  impossible  to  render  satisfactorily  in  one 
printing  a negative  having  a long  range  of  tones,  and 
if  this  type  of  negative  is  employed  a curve  plotted 
for  the  resultant  gum  print  would  have  much  the  same 
appearance  as  the  characteristic  curve  of  the  plate 
given  in  Chapter  III,  the  shadows  being  flat  and  lacking 
in  detail,  the  lights  being  blank  and  only  the  half-tones 
having  the  proper  gradation.  Also  it  is  impossible — * 

194 


MULTIPLE  PRINTING 


or  nearly  so — to  obtain  in  one  printing  of  gum  a rich 
black,  but  both  of  these  objections  may  be  overcome 
by  multiple  printing,  for  repeated  additions  of  pigment 
to  the  shadows  will  give  any  desired  depth  of  color,  and 
it  is  possible  to  print  in  such  a fashion  as  to  render  the 
entire  scale  of  the  negative  satisfactorily. 

If  the  paper  is  coated  and  printed  deep  enough 
to  record  the  gradations  in  the  lights  of  the  negative, 
then  is  dried,  coated  again  and  printed  more  lightly, 
the  half-tones  will  be  recorded  over  the  dark  ground 
left  by  the  half-tones  and  shadows  of  the  first  printing. 
A third  printing  lighter  than  either  of  the  others  will 
record  the  shadows  of  the  negative  and  give  the 
desired  result.  Some  workers  elect  to  print  for  the 
shadows  first,  then  for  the  half-tones  and  finally  for 
the  lights,  but  the  writer  prefers  to  follow  the  order 
given  above,  since  the  other  method  results  in  the 
shadows  of  the  first  printing  and  the  half-tones  of  the 
second  being  covered  by  a gradationless  layer  of  pig- 
ment resulting  from  the  over-printing  of  the  thinner 
portions  of  the  negative  in  the  later  coatings.  Some 
method  of  registration  must  be  used  to  insure  that  the 
outlines  of  successive  printings  coincide,  and  many 
have  been  suggested,  some  of  them  being  as  follows: 

1.  A mask  is  used  as  for  multiple,  carbon  print- 
ing. 

2.  The  paper  is  cut  slightly  smaller  than  the  nega- 
tive and  is  laid  on  it  in  the  printing  frame,  pencil  marks 
being  made  at  the  ends  and  sides,  these  marks,  which  of 
course  are  on  the  back  of  the  paper  and  on  the  face 
of  the  negative,  being  made  to  extend  about  one-half 
inch  in  from  the  edge  of  the  paper  and  as  much  on  the 

195 


TECHNIQUE  OF  GUM 


face  of  the  negative,  the  marks  being  brought  into 
coincidence  for  successive  printing.  This  method  is 
particularly  applicable  to  enlarged  negatives,  in  which 
case  the  large  negative  may  be  made  on  a piece  of 
bromide  paper  or  a dry  plate  a size  or  two  larger  than 
the  finished  picture  is  to  be,  so  that  none  of  the  picture 
will  be  lost  through  cutting  the  printing  paper  smaller 
than  the  negative. 

3.  The  method  which  the  writer  ordinarily  uses 
is  to  use  a printing  frame  a size  larger  than  the  nega- 
tive, to  lay  the  back  of  the  printing  frame  upside  down 
on  a table,  to  place  the  paper  film  side  up  on  this,  lay 
the  negative  face  down  on  the  paper,  and  at  each 
comer  of  the  negative  make  a diagonal  pencil  mark  on 
the  paper,  this  mark  extending  perhaps  an  inch  beyond 
the  negative.  The  glass  of  the  printing  frame  is  then 
laid  on  the  negative  and  the  frame  itself  is  placed 
in  position,  after  which  the  whole  is  turned  over  and 
the  back  is  clamped  in  place. 

4.  A printing  board  is  used  instead  of  a frame, 
this  board  consisting  of  a drawing  board  over  which 
one  or  two  thicknesses  of  felt  have  been  stretched,  the 
felt  being  fastened  by  means  of  tacks  in  the  edges  of 
the  board.  The  paper  is  laid  face  up  on  this  and  the 
negative  is  placed  face  down  on  the  paper.  Stout  pins 
are  then  thrust  into  the  board  in  contact  with  the 
edges  of  the  negative  and  the  whole  is  placed  to  print. 
For  subsequent  printings  the  pins  are  replaced  in  the 
original  holes  in  the  paper  and  the  negative  is  slid  into 
position.  This  gives  accurate  registration  provided  the 
paper  has  been  soaked  and  allowed  to  dry  before  the 
first  printing  in  order  to  shrink  it,  but  it  is  obviously 

196 


MULTIPLE  PRINTING 


inapplicable  to  paper  negatives  unless  a piece  of  glass 
is  laid  over  the  negative,  and  cannot  be  satisfactorily 
used  with  glass  negatives  smaller  than  11X14,  the 
weight  of  smaller  pieces  of  glass  being  insufficient  to 
keep  the  paper  flat. 

Of  course  it  is  not  necessary  that  successive  print- 
ings be  in  the  same  color  any  more  than  is  the  case 
with  carbon,  but  generally  speaking  the  lighter  colors 
should  be  put  on  first  and  the  darker  ones  afterward, 
as  in  the  reverse  instance  the  effect  is  apt  to  be  un- 
pleasant. The  writer  prefers  to  make  the  original 
negative  such  that  the  entire  scale  of  tones  may  be 
rendered  by  one  printing  of  gum  and  to  use  successive 
printings  solely  to  add  richness  and  depth.  The  nega- 
tive for  this  technique  should  be  very  soft  and  should 
be  as  thin  as  possible,  having  no  suggestion  of  fog  or 
heaviness,  partly  because  any  veiling  of  the  shadows 
will  make  it  difficult  to  judge  the  printing  time  and 
partly  because  it  will  be  difficult  to  secure  a bright 
print  from  a veiled  plate.  The  extreme  shadows  of 
the  negative  should  be  almost  clear  glass,  but  the  lower 
tones  should  have  full  detail  and  gradation.  This  type 
of  negative  will  be  secured  by  giving  slight  over- 
exposure and  considerable  under-development  and  will 
be  of  a sort  that  will  give  a bright  clear  print  on  plat- 
inum without  exhausting  more  than  about  half  the 
scale  of  the  ordinary  commercial  paper.  It  may  be 
remarked  that  the  production  of  a negative  precisely 
suited  to  gum  printing  is  probably  the  most  difficult 
technical  feat  in  the  realm  of  pictorial  photography, 
with  the  exception  of  the  production  of  a set  of  nega- 
tives suitable  for  three-color  gum  work. 


197 


TECHNIQUE  OF  GUM 


The  Actinometer.— It  was  said  above  that  an 
actinometer  may  be  made  which  will  facilitate  accuracy 
in  multiple  printing,  and  for  the  information  of  workers 
who  may  desire  to  make  such  an  instrument  instruc- 
tions are  here  given,  these  being  taken  largely  from  the 
very  complete  and  thorough  work  of  Dr.  Kosters, 
entitled  “Der  Gummidruck.” 

A sheet  of  tracing  paper  twelve  inches  long  and 


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Fig.  43. 

four  inches  wide  is  fastened  over  a clean  piece  of  glass 
the  same  size  by  a touch  of  glue  at  each  corner;  another 
piece  the  same  width  but  eleven  and  a half  inches  in 
length  is  fastened  over  this  so  as  to  leave  one-half 
inch  of  the  first  uncovered;  a third  piece  the  same 
width  and  eleven  inches  long  is  then  fastened  over  the 
second  so  as  to  leave  one-half  inch  of  this  and  one  inch 
of  the  first  without  other  covering.  Successive  pieces 
are  then  glued  in  place,  each  piece  being  one-half  inch 
198 


THE  ACTINOMETER 


shorter  than  the  previous  one,  so  that  a photometer  of 
twenty -four  steps  results.  This  is  then  cut  in  two 
so  that  two  photometers  each  twelve  inches  long 
and  two  inches  wide  are  obtained.  These  may  be 
used  either  in  ordinary  printing  frames  or  in  special 
cases  made  for  them  as  shown  in  Figure  43.  The 
lower  portion  of  this  case  serves  to  carry  pieces  of 
test  paper. 

It  is  not  strictly  necessary  to  determine  the  factor 
of  this  instrument,  but  it  is  convenient  to  have  this 
information  and  it  may  be  obtained  in  the  following 
manner:  Slips  of  P.  0.  P.  are  cut  of  the  proper  size  and 
one  is  placed  in  the  instrument  and  exposed  to  light 
for  a definite  period,  say  twenty  seconds;  the  highest 
visible  tint  on  this  print  is  then  noted  (the  different 
steps  should  of  course  be  numbered  in  heavy  figures, 
using  black  drawing  ink)  the  piece  is  then  replaced 
in  the  photometer  and  exposed  to  light  for  another 
definite  period,  say  four  hundred  seconds.  If  now  the 
time  required  for  the  P.  O.  P.  to  show  a visible  tint 
when  exposed  without  the  photometer  is  called  “t” 
and  the  factor  of  the  instrument  is  called  “a”  the 
time  required  for  the  paper  to  show  a tint  under  the 
first  step  of  the  instrument  will  be  tXa  and  the  time 
required  for  it  to  show  a tint  under  the  second  step 
will  be  t X a X a = ta2,  since  each  gradation  of  the 
photometer  absorbs  a certain  percentage  of  the  in- 
cident light.  In  like  manner  the  time  required  for  the 
next  step  to  appear  will  be  t X a X a X a,  that  is,  ta3. 
Then  the  time  required  for  step  “m”  to  appear  will  be 
tam  and  for  step  “n”  to  appear  will  be  tan.  Calling  the 
total  time  required  for  “m”  to  appear  “x,”  and  the 

199 


TECHNIQUE  OF  GUM 


total  time  required  for  “n”  to  appear,  “y”,  then 
we  have 


To  take  a concrete  example,  suppose  tint  4 appears  in 
twenty  seconds  and  tint  8 appears  in  5 minutes  and  20 
seconds,  then  we  have 


and  a equals  2;  that  is,  the  factor  of  the  instrument  is  2, 
which  means  that  each  tint  requires  twice  as  long  to 
appear  as  the  preceding  one,  since  each  step  of  the 
paper  absorbs  half  of  the  incident  light.  Paper  which 
absorbs  this  much  light  would,  however,  give  an  un- 
necessarily extended  scale  of  gradation  and  would  be 
unsatisfactory,  the  most  desirable  factor  being  between 
1.2  and  1.25.  It  should  be  noted  that  most  samples  of 
tracing  paper  will  turn  yellow  with  exposure  to  light 
and  the  factor  will  then  increase  so  that  the  photometer 
must  be  renewed  from  time  to  time.  It  is  convenient  to 
determine  the  factor  of  each  step  of  the  instrument, 
which  can  of  course  be  done  by  obtaining  the  suc- 
cessive powers  of  the  fundamental  factor.  That  is,  if 
a =1.2  this  will  be  the  factor  for  the  first  step,  the 
factor  for  the  second  being  (1.2)2,  that  for  step  three 
being  (1.2)3,  and  so  on.  These  powers  are  most 
readily  obtained  by  the  use  of  a table  of  logarithms, 


tam  = x 
tan  =y 


tan  y 
tam~x 


x 


200 


THE  ACTINOMETER 


which  is  practically  necessary  in  obtaining  the  funda- 
mental factor  of  the  instrument.  This  fundamental 
factor  should  naturally  be  the  average  of  a half  dozen 
or  more  readings,  since  possible  errors  are  thus 
minimized. 

The  method  of  using  this  photometer  is  this:  First 
the  speed  and  scale  of  the  coated  paper  are  determined, 
and  this  is  done  by  placing  a strip  of  the  paper  to  be 
used  for  printing  in  one  of  the  photometers  and  a 
piece  of  P.  O.  P.  in  the  other,  both  photometers  being 
then  exposed  to  light  simultaneously  for  a definite 
length  of  time,  say  ten  minutes,  and  when  they  are 
taken  in  the  highest  visible  tint  on  the  proof  paper  is 
noted.  The  strip  of  gum  paper  is  then  allowed  to 
develop  automatically  for  an  hour  in  water  in  room 
temperature,  when  the  highest  and  lowest  tints  visible 
are  read.  We  will  suppose  that  the  highest  visible 
tint  on  the  P.  O.  P.  is  12  and  the  highest  visible  on 
the  gum  paper  is  14;  this  then  means  that  to  print  to 
a certain  depth  on  this  gum  paper  we  must  always 
print  two  tints  lighter  on  P.  0.  P.  If  the  lowest  tint 
which  is  not  blocked  up  on  the  gum  paper  is  8,  say, 
then  it  is  apparent  that  this  particular  coating  mixture 
will  register  6 steps  of  the  photometer.  The  quality 
of  the  negative  is  then  determined  by  putting  a sheet 
of  P.  0.  P.  into  a printing  frame  with  it  and  a piece  of 
P.  0.  P.  into  one  of  the  photometers.  The  negative 
and  photometer  are  then  put  out  to  print  and  are 
printed  simultaneously  until  the  P.  0.  P.  under  the 
negative  is  printed  proof  deep,  when  they  are  taken  in 
and  the  highest  tint  visible  in  the  photometer  is  read. 
We  will  suppose  this  to  be  10,  and  this  determines  at 

201 


TECHNIQUE  OF  GUM 


once  the  intensity  of  the  lights  in  the  negative  and 
probably  the  scale  of  gradation  also.  Then  when  we 
come  to  print  in  gum  from  this  negative  it  is  apparent 
that  we  shall  wish  to  print  to  tint  10  of  the  gum  paper 
and  this  is  done  by  putting  the  paper  under  the  nega- 
tive and  a strip  of  P.  O.  P.  in  the  photometer  to  print 
simultaneously,  the  exposure  being  just  long  enough  to 
render  tint  8 visible  on  the  test  slip,  for  we  found  that 
the  gum  paper  prints  two  tints  more  rapidly  than  the 
P.  O.  P. 

If  this  method  is  followed  practical  certainty  in 
printing  results,  although  slight  errors  may  be  intro- 
duced owing  to  the  difficulty  of  judging  the  highest 
visible  tint  in  the  photometer.  Still,  variations  in  the 
temperature  of  the  developing  water  will  take  care  of 
this  error.  It  is  apparent  that  if  the  scale  of  the  nega- 
tive is  measured  by  10  tints  of  the  photometer,  it  will 
be  necessary  to  give  the  paper  two  printings  of  this 
particular  gum  mixture,  since  we  found  that  the  coat- 
ing in  question  registered  6 steps  of  the  instrument. 
Should  the  density  of  the  lights  in  the  negative  be 
represented  by  tint  15  of  the  photometer  three  print- 
ings would  evidently  be  required.  Obviously,  in  the 
first  case  the  second  print  would  be  such  as  to  register 
tint  4;  that  is,  printing  would  be  continued  until  tint 
2 of  the  photometer  becomes  visible,  and  in  the  other 
case  the  second  printing  would  be  for  tint  7 and  the 
third  for  tint  1. 

The  relative  sensitiveness  of  a bichromate-sensitized 
colloid  film  as  compared  to  P.  O.  P.  is  greater  in  a weak 
light  than  in  a strong  one,  so  that  if  the  determinations 
indicated  above  of  the  relative  printing  depths  of 

202 


FAILURES 


P.  O.  P.  and  of  gum  paper  are  made  on  a bright  day 
during  the  hours  when  the  light  is  strongest,  it  will  be 
found  that  printing  by  this  method  will  result  in 
excessive  exposure  of  the  gum  paper  when  the  work  is 
done  early  in  the  morning  or  late  in  the  afternoon  or 
on  a dull  day.  This  error  may  be  avoided  by  using  in 
the  photometer  freshly  prepared  strips  of  paper  coated 
with  a bichromate-sensitized  gum  film,  this  being  made 
by  coating  a piece  of  paper  with  a standard  mixture  of 
gum  solution  and  sensitizer,  using  no  pigment  at  all, 
and  this  is  dried  in  the  dark,  when  it  may  be  cut  up 
into  slips  and  used  for  test  purposes..  Evidently  the 
relative  sensitiveness  of  this  test  paper  to  strong  and 
weak  light  will  be  the  same  or  nearly  the  same  as  that 
of  the  printing  paper,  and  the  numbers  of  the  acti- 
nometer  may  be  read  directly  upon  it,  there  being  no 
pigment  to  mask  the  color  of  the  bichromate  image. 

Some  workers  give  ten  or  twelve  printings  and  the 
writer  has  even  heard  of  one  who  habitually  gives  from 
twenty-five  to  thirty,  but  any  such  number  of  print- 
ings is  quite  excessive,  since  a suitably  adjusted  coat- 
ing mixture  will  give  any  richness  of  shadows  which 
may  be  required  in  four  printings  and  will  render  the 
gradations  of  practically  any  negative  in  from  four  to  six. 

Failures. — As  has  been  said,  gum  is  the  most 
flexible  of  all  printing  mediums,  and  for  this  reason 
failures  are  more  apt  to  occur  than  with  any  other. 
If,  however,  the  worker  has  a good  grasp  of  the  prin- 
ciples of  the  process  he  will  be  able  to  determine  for 
himself  the  cause  of  any  particular  defect,  though  a 
few  of  the  commoner  ones  are  noted  here. 

Over-printing  and  under-printing  of  course  manifest 

203 


TECHNIQUE  OF  GUM 


themselves  by  the  print  either  requiring  an  undue 
length  of  time  for  development  or  developing  too 
rapidly.  If  the  trouble  is  over-printing  the  lights  of 
the  picture  will  remain  dark,  but  the  margins  of  the 
print  which  were  protected  by  the  rebate  of  the  printing 
frame  will  develop  clear.  Should  the  margins  fail  to 
develop  clear  in  half  an  hour,  the  trouble  is  due  to  an 
excess  of  pigment  in  the  mixture,  the  paper  being 
stained,  to  staleness  of  the  paper,  or  to  the  fact  of  the 
paper  having  been  exposed  to  light  when  not  in  the 
printing  frame. 

If  the  print  flakes  in  development,  that  is,  the  gum 
peels  off  in  patches  instead  of  developing  smoothly, 
the  trouble  is  due  to  one  of  five  causes:  1.  Excess  of 
pigment  in  the  coating  mixture,  this  indicating  itself  of 
course  by  stained  lights.  2.  The  application  of  too 
thick  a coating  of  the  mixture  to  the  paper.  Only 
experience  can  determine  the  proper  thickness  of  the 
coating,  but  it  may  be  said  that  the  prepared  paper 
should  not  in  general  appear  black  but  rather  of  a 
medium  or  dark  gray,  the  coating  being  thin  enough  to 
allow  the  paper  to  be  seen  slightly  through  it.  3. 
Excess  of  gum  in  the  coating  mixture.  This  will  show 
itself  at  the  time  of  coating  the  paper,  since  too  thick 
a mixture  will  be  difficult  to  spread  and  will  become 
tacky  so  rapidly  that  it  will  be  difficult,  if  not  impossible, 
to  blend  it  properly.  4.  Too  much  alkali  in  the 
developing  water.  5.  Excessive  amount  of  size  in  the 
paper.  If  this  last-named  fault  is  the  cause  of  the 
trouble  it  can  be  determined  only  by  the  fact  that 
it  is  not  due  to  any  of  the  other  causes  given. 

If  the  print  shows  a streaky  texture  this  may  be 

204 


FAILURES 


due  either  to  faulty  blending  or  to  removing  the  print 
from  the  developing  tray  too  soon  and  hanging  it  up  to 
dry.  In  the  former  case  the  streaks  will  be  compara- 
tively fine  and  may  be  in  any  direction,  either  vertical, 
horizontal  or  oblique.  In  the  latter  case  they  will  be 
broader  in  character  and  their  direction  will  of  course 
depend  on  the  position  assumed  by  the  print  in  drying. 
Streaks  caused  by  faulty  blending  will  be  apparent  on 
the  paper  before  it  is  printed. 

A general  running  of  the  image  is  due  to  under- 
printing or  to  insufficient  development.  Under-printing 
will  of  course  show  itself  in  the  developing  tray. 

Staleness  of  the  paper  will  manifest  itself  by  a 
refusal  to  develop  and  is  difficult  to  distinguish  from 
the  effect  of  excessive  pigment  in  the  mixture  when 
the  excess  is  not  sufficient  to  cause  flaking.  Gum 
paper  deteriorates  very  rapidly  and  should  be  kept  in 
a sealed  platinum  tin  with  preservative  unless  it  is  to  be 
used  immediately  after  drying.  Even  if  kept  in  this 
manner  it  does  not  remain  in  first-class  condition  for 
more  than  a day  and  may  become  entirely  useless  in 
two  or  three  days,  owing  to  the  insolubilization  of 
the  gum  which  takes  place  even  without  exposure  to 
light. 


CHAPTER  XIII 

TECHNIQUE  OF  GUM-PLATINUM 

The  reasons  for  adding  a printing  of  gum  to  a 
platinum  print  have  already  been  given,  and  little  can 
be  said  concerning  the  technique  of  the  process,  since 
this  is  covered  under  the  headings  of  platinum  and 
gum,  the  process  consisting  simply  of  making  a platinum 
print  and  using  that  as  a paper  on  which  to  make  one 
or  more  gum  prints. 

It  will  be  found  convenient  to  make  the  platinum 
print  on  a sheet  of  paper  somewhat  larger  than  the 
negative,  since  this  facilitates  the  application  of  the 
gum  coating.  This,  however,  is  not  strictly  necessary, 
for  by  careful  working  it  is  possible  to  coat  up  to  the 
very  edges  of  the  print. 

In  practically  all  cases  it  will  be  found  desirable  to 
size  the  platinum  print  before  applying  the  gum,  and 
this  may  conveniently  be  done  with  a boiled  starch 
paste  as  indicated  in  the  chapter  on  gum  printing,  this 
being  easier  to  prepare  than  the  gelatine  size  and 
being  usually  sufficient,  since  it  rarely  happens  that 
more  than  one  printing  of  gum  will  be  given.  The 
necessity  for  sizing  is  due  to  the  fact  that  the  various 
chemical  baths  which  the  platinum  print  goes  through 
have  a strong  tendency  to  remove  the  size  from  the 
paper. 

The  gum  mixture  should  ordinarily  be  rather  weaker 
in  pigment  than  for  straight  gum  printing,  since  the 
platinum  print  itself  furnishes  fairly  rich  blacks  and 

206 


CHIEF  VALUE 


the  purpose  of  the  gum  is  to  add  somewhat  to  their 
value. 

It  is  not  necessary  to  adopt  any  special  methods 
of  registration  in  gum-platinum  work,  this  being  very 
easily  effected  by  placing  the  print  on  the  negative  in 
a printing  frame,  holding  it  up  to  a concentrated  light, 
such  as  a Welsbach  light,  in  a relatively  dark  room  and 
shifting  the  print  about  with  the  fingers  until  it  is 
seen  to  be  registered,  when  the  frame  is  carefully 
lowered  to  the  table  and  the  back  clamped  in,  the 
print  being  held  in  position  on  the  negative  while 
clamping  the  first  section  of  the  back  in  place.  If  a 
printing  frame  the  size  of  the  negative  is  used  it  will  be 
found  desirable  to  trim  the  print  about  one-sixteenth 
inch  smaller  all  around  than  the  negative  before 
attempting  to  register.  The  fact  that  this  method  is 
possible  in  gum-platinum  but  not  in  gum  is  due  to  the 
much  greater  opacity  of  the  platinum  image  as  com- 
pared to  that  of  the  gum.  If  two  or  three  printings 
have  been  given  to  a gum  print  it  may  then  be  regis- 
tered by  this  method  if  desired,  and  in  any  case  it  will 
be  easier  to  register  the  print  if  the  negative  is  toward 
the  worker  than  if  it  is  between  the  print  and  the  light. 

Development  of  a gum-platinum  print  should  in 
general  be  largely  automatic,  since  brush  work  is  more 
noticeable  in  this  case  than  in  straight  gum  printing, 
owing  to  the  much  more  definitely  photographic  char- 
acter of  the  platinum  image.  It  is,  however,  possible 
to  intensify  the  lights  to  a certain  extent  without  the 
effect  being  conspicuous. 

Gum-platinum  is  useful  in  many  ways,  such  as  for 
the  purpose  of  obscuring  shadow  detail  which  is  not 

207 


TECHNIQUE  OF  GUM-PLATINUM 


desired  or  for  adding  color  to  the  print,  but  in  the 
writer’s  opinion  its  chief  value  is  found  in  portraiture. 
Yellow  and  red,  which  characterize  the  major  portions 
of  the  face,  are  colors  which  have  strong  psychic  value; 
that  is,  they  are  unconsciously  associated  in  our  minds 
with  light  and  warmth  and  hence  appear  much  stronger 
than  their  true  photometric  value;  also,  in  conversing 
with  an  individual  or  in  looking  at  one  at  a short 
distance,  the  attention  as  a rule  is  concentrated  on  the 
face,  so  that  the  clothing  appears  to  us  rather  indeter- 
minate, except  in  the  case  of  a noticeably  dressed  woman. 
For  this  reason  our  ordinary  impression  of  a Caucasian 
is  of  a light  area  surmounting  a darker  or  less  defined 
area  representing  the  clothing.  Careful  analysis  shows 
that  the  skin  is  in  reality  much  darker  than  white 
linen  and  many  photographers  attempt  to  render  this 
relationship  rather  than  the  true  psychic  relationship 
by  making  the  face  considerably  darker  than  the  collar 
or  other  white  portions  of  the  cloth,  so  that  they  rep- 
resent accurately  a minor  truth — the  values  of  the 
linen — at  the  expense  of  a greater  one.  On  the  other 
hand,  if  the  photographer  desires  to  give  the  true 
impression  he  usually  endeavors  to  accomplish  this 
through  either  under-exposure  or  over-development 
of  the  negative,  the  former  obliterating  shadow  detail 
by  failure  to  render  it  on  the  plate,  the  second  oblit- 
erating it  by  necessitating  over-printing  of  the  shadows 
in  order  to  record  the  gradations  in  the  lights.  Either 
of  these  methods  gives  a scale  of  tones  which  is  quite 
as  false  as  that  resulting  from  the  technique  first 
mentioned,  since  both  methods  extend  the  scale  of 
tones  in  the  face  unduly. 

208 


CHIEF  VALUE 


The  desired  effect  may  readily  be  obtained  without 
falsifying  the  values  in  the  face  by  making  a normal 
negative,  erring  on  the  side  of  under-development 
rather  than  over-,  and  making  from  this  negative  a 
gum-platinum  print,  for  the  platinum  will  render  the 
scale  of  the  face  as  it  should  be  rendered  and  the 
additional  printing  of  gum  will,  if  properly  adjusted, 
subdue  the  shadow  detail  without  extending  unduly  the 
gradation  in  the  features.  In  addition,  the  increased 
weight  given  to  the  shadows  by  the  gum  printing 
without  a corresponding  increase  of  weight  in  the  lights 
will  tend  to  emphasize  the  latter  by  means  of  contrast, 
and  the  writer  finds  that  a portrait  handled  in  this 
manner,  especially  if  it  be  of  a strong-featured  man, 
is  exceedingly  effective.  For  children  and  for  women 
in  light  clothes  it  is  not  so  much  to  be  recommended, 
though  a soft  negative  printed  in  gum-platinum  will  in 
the  case  of  a satin  gown  give  a quality  of  texture  to  the 
cloth  which  the  writer  has  never  seen  equalled  in  any 
other  printing  medium  except  oil. 

It  is  much  easier  to  make  a gum-platinum  print 
than  to  make  a gum  print,  since  in  the  first  case  it  is 
simply  a question  of  adding  a certain  amount  of 
weight  to  an  already  nearly  completed  print,  and  the 
worker  is  not  as  a rule  obliged  to  consider  the  question 
of  rendering  the  gradations  of  the  negative  with  the 
same  care  as  is  necessary  in  gum  printing.  It  will, 
however,  be  found  much  easier  to  make  a gum-platinum 
if  the  platinum  print  was  normally  exposed  so  that  the 
lights  are  rendered  satisfactorily  and  weight  is  added 
merely  to  the  half-tones  and  shadows  than  if  the 
platinum  print  was  under-exposed  and  an  attempt  is 

14  209 


TECHNIQUE  OF  GUM-PLATINUM 


made  to  add  by  means  of  the  gum  gradation  which  is 
lacking  in  the  lights.  This  is  due  to  the  fact  that  in 
many  circumstances  the  gum  process  has  a tendency 
to  flatten  the  lights,  this  resulting  from  the  transparence 
of  the  pigment  in  the  upper  register  unless  enough  is 
added  to  cause  flaking  in  the  shadows.  Also  it  will 
be  found  that  gum-platinum  presents  a considerable 
economy  of  time  and  effort  over  multiple  gum,  for  the 
reason  that  platinum  paper  will  render  shadows  as 
dark  and  a scale  of  gradation  as  full  as  can  be  obtained 
in  two  or  three  printings  of  gum,  so  that  the  original 
platinum  print  represents  in  its  values  the  equivalent 
of  perhaps  three  gum  printings,  and  is  made  with 
much  less  effort.  Further,  unless  extreme  care  is 
taken  in  registering  successive  printings  it  will  be  found 
that  each  additional  printing  of  gum  tends  to  add  a 
looseness  to  the  outlines  of  the  image,  even  though  the 
registration  is  not  so  bad  as  to  give  definite  double 
outlines,  for  which  reason  gum-platinum  tends  to  pre- 
serve the  accuracy  of  drawing  of  the  negative  with 
greater  precision  than  is  the  case  with  multiple  gum, 
though  the  shrinking  of  the  platinum  print  will  often 
make  precise  registration  impossible.  In  such  a case 
the  most  important  parts  should  be  registered,  and 
the  faulty  outlines  may  often  be  remedied  by  a few 
touches  of  a pencil  on  the  finished  print. 


CHAPTER  XIV 


TECHNIQUE  OF  OIL  AND  BROMOIL  AND  OF 
TRANSFERRING 

Theory  of  Oil. — Oil  printing  is  practically  iden- 
tical with  the  reproductive  process  known  as  collotype 
except  that  the  support  is  paper  instead  of  glass  and 
that  a brush  is  generally  used  for  applying  the  ink, 
though  in  some  cases  a roller  is  used  for  this  purpose 
as  in  collotype  work.  If  a film  of  unhardened  gelatine 
is  spread  uniformly  on  a sheet  of  paper  and  when  dry 
is  sensitized  with  a solution  of  a bichromate  salt,  this 
gelatine  film  will  on  exposure  to  light  under  the  nega- 
tive be  tanned  in  proportion  to  the  amount  of  light 
action;  that  is,  the  shadows,  which  have  received  the 
most  light,  will  be  strongly  tanned,  the  half-tones  less 
so  and  the  lights  least  of  all.  If  the  sensitizer  is  then 
washed  out  of  the  film  and  the  print  is  soaked  for  a 
few  minutes  in  warm  water,  the  less  tanned  portions 
absorb  water  more  freely  than  those  which  have 
received  greater  light  action  and  acquire  the  property 
of  repelling  an  oily  ink,  the  degree  of  repulsion  of  the 
ink  depending  on  the  amount  of  water  in  the  film. 

Theory  of  Bromoil. — In  the  case  of  bromoil  the 
print  is  made  either  by  contact  printing  or  by  enlarge- 
ment on  a sheet  of  bromide  paper  which  is  developed, 
fixed,  and  washed  in  the  usual  manner.  This  print  is 
then  treated  with  a solution  of  certain  chemicals,  the 
effect  being  to  tan  the  gelatine  in  proportion  to  the 
amount  of  silver  contained  in  the  film.  Hence  the 
shadows  are  most  tanned,  the  half-tones  less  and  the 

211 


TECHNIQUE  OF  OIL  AND  13  R G M OIL 


lights  least  of  all.  Washing  and  soaking  results  in  the 
gradations  of  the  print  assuming  in  varying  degrees  the 
power  of  repelling  a greasy  ink  exactly  as  is  the  case 
in  oil  printing. 

Theory  of  Transferring. — The  oil  or  bromoil 
print  is  prepared  and  inked  in  the  usual  manner,  using 
a somewhat  softer  ink  than  is  generally  employed. 
This  print  is  then  placed  in  contact  with  a sheet  of 
paper,  which  should  not  be  too  heavily  sized,  and  the 
two  are  run  through  a roller  press,  such  as  an  etching 
press  or  a clothes  wringer.  The  result  is  that  most  if 
not  all  of  the  ink  from  the  image  in  the  oil  or  bromoil 
print  is  transferred  to  the  uncoated  paper  and  the 
final  result  somewhat  resembles  a lithograph. 

Materials  Required. — The  paper  should,  as  has 
been  said,  be  coated  with  a film  of  unhardened  gela- 
tine, and  commercial  oil  papers  are  obtainable,  but  the 
writer  finds  that  the  most  satisfactory  oil  paper  with 
which  he  is  acquainted  is  made  by  taking  a good  bro- 
mide paper  which  has  not  been  hardened  in  manufac- 
ture, fixing  it  without  exposure  to  light  in  a 20  per  cent, 
plain  hypo  bath,  washing  for  one  hour  in  running  water 
and  drying.  The  paper  thus  prepared  will  keep  almost 
indefinitely,  a small  amount  being  sensitized  as  required. 
Generally  speaking  the  smooth  grade  is  to  be  preferred, 
though  in  some  cases  the  rough  may  be  desirable. 

The  sensitizer  is  a solution  of  potassium,  sodium 
or  ammonium  bichromate,  and  the  most  generally  useful 
strength  is  a 2}^  per  cent,  solution;  that  is,  480  grains 
of  the  salt  dissolved  in  40  ounces  of  water,  though  for 
some  purposes  the  bath  may  be  used  stronger  or  weaker 
than  this. 

213 


THE  DRIVING  WIND 
BY  PAUL  L.  ANDERSON 
From  an  Oil  Print 


MATERIALS  REQUIRED 


A half  dozen  lintless  blotters  a size  larger  than  the 
paper  to  be  printed  are  necessary,  as  well  as  several 
soft  lintless  cloths,  well-washed  linen  or  cotton  hand- 
kerchiefs being  the  most  desirable  which  the  writer 
knows. 

Inks  will  be  required,  and  these  may  be  either  the 
specially  prepared  inks  furnished  by  the  manufacturers 
of  oil  printing  supplies  or  stiff  lithographic  inks,  the 
latter  being  obtained  from  any  dealer  in  printers’  inks 
and  being  preferably  packed  in  collapsible  metal  tubes. 
These  inks  may  be  obtained  in  tubes  of  varying  size 
and  when  purchased  in  quarter-pound  tubes  are  not 
only  quite  as  satisfactory  as  the  specially  prepared 
inks  but  cost  something  like  one-tenth  as  much  as  the 
latter.  Brushes  will  be  needed,  and  these  are  of  a 
special  type,  being  known  when  prepared  for  oil  printing 
as  “stag  foot  oil  printing  brushes”  and  when  purchased 
of  a dealer  in  painters’  supplies  as  “fitch  stipplers,  cut 
slanting.”  The  French  and  English  oil  brushes  cost 
about  twice  as  much  as  the  American  made  fitch 
stipplers  and  are  worth  the  difference.  It  will  be  found 
desirable  to  have  at  least  three  brushes,  one  about  one- 
eighth  or  one-fourth  inch  diameter  for  fine  work  and 
two  about  one  inch  diameter  or  larger  for  general  use. 
If  prints  larger  than  11X14  inches  are  to  be  made  it 
will,  however,  be  found  desirable  to  have  the  larger 
brushes  of  the  largest  size  which  can  be  obtained, 
since  the  use  of  a small  brush  on  large  prints  prolongs 
unduly  the  time  required  for  inking. 

Either  gasoline  or  soap  and  water  may  be  used  for 
cleaning  the  brushes,  and  this  should  be  done  im- 
mediately on  the  completion  of  inking,  since  if  the  ink 

213 


TECHNIQUE  OF  OIL  AND  BROMOIL 


is  allowed  to  dry  on  the  brushes  it  will  be  difficult  to 
remove.  The  brushes  when  not  in  use  should  be  kept 
in  paper  cones  to  preserve  their  shape.  A sheet  of  glass 
about  8X10  inches  or  a china  palette  will  be  required, 
and  it  is  convenient  to  have  a palette  knife,  although 
this  is  not  strictly  necessary.  Some  medium  for  thin- 
ning the  ink  will  be  required  at  times  and  this  may  be 
either  boiled  linseed  oil,  turpentine,  megilp  or  Rober- 
son’s or  Sinclair’s  medium.  A very  small  amount  is 
sufficient  and  an  ounce  of  any  of  these  will  probably 
last  the  ordinary  worker  many  years. 

It  is  convenient  though  not  imperative  to  have  a 
board  on  which  to  place  the  print  for  inking  and  this 
may  conveniently  be  made  as  follows:  An  ordinary 
draftsman’s  drawing  board  of  suitable  size  is  either 
given  three  coats  of  spar  varnish  or  is  covered  with 
oilcloth  drawn  smoothly  over  the  surface  and  tacked 
firmly  along  the  edges.  A piece  of  well- washed  muslin 
slightly  larger  than  the  board  is  tacked  to  one  end  of 
the  latter  so  that  six  or  eight  wet  blotters  may  be  laid 
on  the  oilcloth  and  the  muslin  drawn  over  them,  being 
fastened  in  place  with  push-pins. 

Sensitizing. — As  stated  above,  the  best  strength 
of  sensitizer  for  general  use  is  a per  cent,  solution, 
though  it  may  be  used  as  weak  as  1 per  cent,  if  more 
contrast  is  desired  or  as  strong  as  5 per  cent,  if  softer 
prints  are  wanted.  Weakening  the  sensitizer  does  not 
interfere  with  precision  in  exposure,  as  is  the  case  in 
carbon  printing,  since  the  image  prints  out  to  a cer- 
tain extent  and  the  time  of  printing  is  gauged  by  the 
appearance  of  the  paper  in  the  frame.  The  method 
of  use  is  the  same  as  in  the  case  of  carbon;  that  is,  the 

214 


SENSITIZING 


paper  is  immersed  for  two  and  one-half  minutes  and  is 
then  squeegeed  face  down  on  a clean  piece  of  glass  to 
remove  the  excess  of  sensitizer  and  is  hung  up  to  dry 
in  the  dark.  The  use  of  the  ferrotype  plate  presents  no 
advantage  in  oil  printing  and  retards  drying  somewhat, 
since  only  one  surface  of  the  paper  is  exposed  to  the  air. 
As  with  carbon  and  gum,  sensitizing  may  be  done  in 
an  ordinary  room,  but  drying  must  take  place  in  the 
dark,  oil  paper  when  dry  being  much  more  sensitive 
to  light  than  carbon.  A sensitized  oil  paper  deteriorates 
more  rapidly  than  carbon  tissue,  and  is  at  its  best 
immediately  after  drying,  though  if  carefully  kept  it 
may  remain  in  fair  working  condition  for  a few  days. 
A quick -drying  sensitizer  may  be  used,  and  many 
workers,  including  the  writer,  prefer  this  both  because 
of  its  greater  flexibility  and  because  of  the  rapid  dete- 
rioration of  sensitized  tissue,  the  spirit  sensitizer  making 
it  possible  to  sensitize  and  print  on  the  same  day.  A 
good  formula  follows: 

Stock  solution. 

Water 4 ounces 

Sodium  bichromate 4 ounces 

For  use  take 

Stock  solution 1 to  8 drams 

Alcohol,  95  per  cent,  to  make  total  volume  2 ounces 

This  is  spread  evenly  over  the  paper  with  a Blanchard 
brush  or  a flat  Japanese  paint  brush,  and  if  a standard 
amount  is  used  for  a given  size  of  sheet  the  results  will 
be  uniform.  This  sensitizer  dries  so  rapidly  that  it 
should  be  applied  by  artificial  light  or  in  weak  daylight. 
The  paper  will  dry  in  from  five  minutes  to  half  an  hour, 
depending  on  the  proportion  of  alcohol  and  on  the 
atmospheric  conditions,  the  stronger  sensitizer  being  of 
course  used  for  soft  results. 


215 


TECHNIQUE  OF  OIL  AND  BROMOIL 


Printing. — The  best  type  of  negative  for  oil 
printing,  that  is,  one  which  will  exhaust  the  possibilities 
of  the  process,  is  one  which,  although  by  no  means 
harsh,  should  nevertheless  have  more  contrast  than  for 
gum  work.  It  will  give  a moderately  bright  print  in 
platinum,  though  it  will  by  no  means  exhaust  the  scale 
of  platinum  paper,  and  since  the  oil  process  tends  to 
soften  outlines  somewhat  these  should  have  in  the 
negative  rather  more  firmness  of  drawing  than  for  an 
equivalent  amount  of  diffusion  in  platinum  or  carbon. 

Printing  is  done  by  sunlight  or  strong  artificial 
light  and  should  be  continued  until  the  highest  lights 
of  the  picture  have  a slight  tone,  unless,  as  is  sometimes 
the  case,  a pure  white  is  desired  in  the  lights,  the 
appearance  of  the  print  in  the  frame  being  very  similar 
to  that  of  a piece  of  platinum  paper  in  the  same  cir- 
cumstances. When  exposure  is  complete  the  print 
should  at  once  be  washed  in  water  at  about  room 
temperature  until  all  the  free  sensitizer  has  been  re- 
moved. It  will  not  be  possible  to  wash  out  all  traces 
of  the  image,  since  a certain  amount  of  tone  will  always 
remain  in  the  shadows.  Washing  should  not  be  delayed, 
for  the  continuing  action  of  light  is  the  same  with  oil 
as  with  carbon  and  gum.  After  the  print  is  thoroughly 
washed  it  may  either  be  soaked  and  inked  at  once  or 
may  be  hung  up  to  dry  and  kept  for  an  indefinite  period, 
any  further  change  in  the  gelatine  film  taking  place 
with  extreme  slowness.  The  writer  has  known  of  prints 
which  had  been  thoroughly  washed  being  inked  satis- 
factorily six  months  after  printing,  but  the  film  will  in 
time  deteriorate  and  the  ink  will  not  take  properly. 

It  is  necessary  to  employ  a safe-edge  and  this  should 

216 


SOAKING 


be  rather  wider  than  for  the  carbon  process,  half  an 
inch  being  none  too  much,  since  the  purpose  of  the  safe- 
edge  is  to  keep  the  inking  brush  from  touching  the 
wet  pad  on  which  the  print  must  rest  during  inking, 
for  if  the  brush  takes  up  any  water  it  will  not  deposit 
the  ink  properly.  The  safe-edge  also  furnishes  a 
convenient  indication  of  the  correctness  of  both  expo- 
sure and  soaking,  since  if  the  print  is  properly  handled 
the  margin  will  remain  clear  both  in  the  printing  frame 
and  in  the  inking.  Very  pleasing  effects  may  be  ob- 
tained by  using  paper  a size  larger  than  the  negative, 
i.  e.,  11X14  for  an  8X10  plate,  printing  with  a mask 
in  the  frame,  and  leaving  the  entire  margin  to  serve 
as  a border.  If  the  ink  takes  on  the  edge  it  may  be 
removed  before  hanging  the  print  up  to  dry,  by  wiping 
with  a damp  cloth  wrapped  about  the  finger. 

Soaking. — After  washing  the  print  must  be  soaked 
for  a few  minutes  in  warm  water  and  no  definite  instruc- 
tions can  be  given  for  this  part  of  the  process,  the 
degree  of  soaking  varying  with  circumstances.  If  the 
print  has  been  over-exposed,  warmer  water  will  be 
needed  for  soaking  than  if  printing  has  been  normal, 
increase  of  temperature  in  the  soaking  water  causing 
the  film  to  absorb  a greater  amount  of  water  than  would 
otherwise  be  the  case,  thus  giving  it  a greater  repellent 
effect  on  the  ink.  It  will  be  apparent  from  this  that 
the  use  of  warmer  water  not  only  means  a higher  value 
in  the  lights  but  also  gives  the  print  greater  contrast, 
since  the  lights  are  more  affected  than  the  half  tones 
and  these  in  turn  more  than  the  shadows.  If  it  is 
found  on  inking  that  the  print  has  been  soaked  in 
water  at  too  high  a temperature,  which  is  indicated  by 

217 


TECHNIQUE  OF  OIL  AND  BROMOIL 


the  lights  refusing  to  take  the  ink  properly,  it  may  be 
allowed  to  dry  out  partially.  About  the  only  guide 
which  can  be  given  in  the  matter  of  soaking  is  to  say 
that  a normally  exposed  print  should  be  soaked  in 
water  at  such  a temperature  that  the  gelatine  film  on 
the  unexposed  margins  which  were  protected  by  the 
safe-edge  should,  on  rubbing  between  the  thumb  and 
finger,  rub  off  with  moderate  ease,  though  this  applies 
especially  to  the  commercial  oil  papers,  such  a marked 
softening  being  unnecessary  with  the  bromide  paper. 
If  any  doubt  is  felt  as  to  the  sufficiency  of  the  soaking, 
a corner  of  the  print  may  be  surface-dried  and  the  ink 
tried  on  the  dry  area.  If  the  ink  takes  on  the  print 
but  fails  to  adhere  to  the  safe-edge  the  soaking  is 
probably  correct. 

Generally  speaking,  the  soaking  should  end  in  water 
at  about  110°  Fahrenheit,  and  better  results  will  be 
obtained  if  the  soaking  is  begun  in  water  at  about  95° 
Fahrenheit,  the  temperature  of  the  water  being  grad- 
ually raised  to  the  proper  point,  than  if  the  print  is 
placed  at  once  into  the  warmer  water.  In  case  of 
serious  over-printing  the  water  may  be  used  much 
hotter  than  this,  though  excessive  heat  will  probably 
cause  the  gelatine  of  the  safe-edge  to  tear  during  the 
inking.  When  the  print  has  been  sufficiently  soaked, 
which  will  probably  require  about  ten  or  fifteen  minutes, 
it  is  lifted  from  the  tray,  drained,  and  placed  face  up  on 
a sheet  of  glass  or  other  smooth  surface.  It  is  then 
dabbed  lightly  with  a wad  of  lintless  absorbent  cloth 
until  surface-dry,  when  it  is  laid  on  a pile  of  half  a 
dozen  wet  blotters  or  on  the  inking  board  described 
above,  and  inking  may  be  begun. 

218 


INKING 


Inking. — The  final  result  depends  in  great  measure 
on  the  character  of  the  ink  and  the  method  of  its 
application,  and  experience  is  the  only  satisfactory 
guide  in  these  matters.  A small  quantity  of  the  ink  is 
squeezed  from  the  tube  on  a clean  piece  of  glass  or  a 
china  palette  and  is  spread  out  in  a film  about  one- 
sixteenth  inch  thick  by  means  of  the  palette  knife.  A 
quantity  of  ink  the  size  of  a large  pea  will  serve  to  ink 
three  or  four  8X10  prints.  One  of  the  large  brushes — 
which  are  cut  to  a slant,  the  ends  of  the  hairs  being 
slightly  domed — is  dabbed  lightly  in  the  ink  and  is 
then  dabbed  two  or  three  times  on  a clean  portion  of  the 
palette  in  order  to  distribute  the  ink  among  the  hairs. 
The  brush  is  then  pressed  with  only  moderate  force  on 
the  print,  when  it  will  be  found  to  leave  some  of  the 
ink  on  the  film.  After  two  or  three  touches  of  the 
brush  on  the  print  it  must  be  dabbed  in  the  ink  again 
and  the  ink  distributed  as  before,  the  operation  being 
repeated  until  the  print  is  satisfactorily  inked.  It  will 
be  found  advantageous  when  dabbing  the  brush  on 
the  palette  to  distribute  the  ink  to  dab  always  in 
approximately  the  same  part  of  the  palette,  since  an 
exceedingly  thin  film  of  ink  is  thus  deposited  on  the 
palette,  and  the  brush  will  work  better  than  if  a fresh 
spot  is  chosen  each  time.  Some  workers  advise  inking 
either  the  high  lights  or  the  shadows  up  to  their  proper 
value  at  first  and  then  proceeding  to  the  rest  of  the 
print,  but  the  writer  prefers  to  ink  lightly  over  the  entire 
area  of  the  print  at  first,  gradually  building  up  to  the 
desired  degree  of  contrast,  the  effect  being  thus  more 
directly  under  the  control  of  the  worker.  The  appear- 
ance of  the  print  will  probably  be  very  discouraging  at 

219 


TECHNIQUE  OF  OIL  AND  BEOMOIL 


first,  but  inking  should  be  continued  and  the  image  will 
gradually  attain  its  proper  character  if  the  preceding 
operations  have  been  correctly  carried  out. 

There  are  two  methods  of  handling  the  brush,  and 
these  produce  widely  differing  results.  A slow  pressure 
of  the  brush  on  the  print  deposits  ink  on  the  film, 
whereas  a quick  4 ‘hopping”  action  removes  ink  already 
adhering,  this  effect  being  especially  noticeable  when  a 
clean  brush  is  used.  If  it  is  found  difficult  to  deposit 
sufficient  ink  to  obtain  the  desired  depth  in  the  shadows 
the  ink  may  be  thinned  with  any  of  the  mediums 
mentioned  above,  the  least  desirable  of  them  being 
turpentine,  and  there  being  practically  no  choice  among 
the  others.  The  ink  will  probably  be  sufficiently 
thinned  if  a single  drop  of  the  medium  is  placed  on  a 
clean  piece  of  glass  and  the  palette  knife  is  lightly 
dipped  in  this  drop,  the  small  quantity  adhering  being 
then  mixed  with  the  ink.  The  possibilities  of  increasing 
the  contrast  in  this  manner  are  unlimited,  since  if  the 
ink  is  sufficiently  thinned  it  is  possible  to  produce  an 
absolute  black  even  on  the  safe-edge,  and  a great  deal 
may  be  done  to  lighten  the  values  by  hopping,  this 
hopping  action  being  easier  to  effect  when  only  a slight 
amount  of  ink  has  been  deposited  on  the  print.  It  is 
difficult  to  describe  precisely  the  method  of  hopping, 
but  it  consists  essentially  in  allowing  the  brush  to 
strike  the  film  with  moderate  vigor  and  removing  it 
suddenly  from  contact.  Some  writers  say  that  hopping 
is  done  by  allowing  the  brush  to  fall  on  the  print  and 
catching  it  on  the  rebound,  but  the  writer  prefers  to 
throw  it  lightly  against  the  film  and  then  catch  it  as  it 
leaves  the  print. 

220 


INKING 


It  will  be  seen  that  unlimited  possibilities  of  control 
of  relative  values  and  of  total  contrast  inhere  in  the 
process,  since  it  is  possible  to  deposit  as  much  or  as 
little  ink  on  a given  area  as  may  be  desired,  even  leav- 
ing it  off  entirely,  and  it  is  also  possible  to  remove 
much  of  the  ink  which  has  already  been  deposited. 
Some  writers  advocate  inking  the  print  at  once  for 
a normal  result,  afterward  lightening  portions  by 
hopping,  but  the  writer  prefers  to  work  with  a guide 
print,  for  example,  a P.  0.  P.  proof,  before  him  and  to 
deposit  ink  only  where  it  is  needed  for  the  desired 
pictorial  effect,  since  it  is  not  possible  to  remove  an 
indefinite  amount  by  hopping.  Brush-holders  for 
hopping  may  be  obtained,  these  consisting  of  a piece 
of  spring  wire  several  inches  long,  having  at  one  end 
a handle  and  at  the  other  a device  for  holding  the 
brush.  The  writer  has  found  that  the  use  of  such  a 
holder  is  very  likely  to  result  in  tearing  of  the  gelatine 
film. 

The  texture  of  an  oil  print  is  practically  always 
slightly  grainy,  since  each  individual  hair  of  the 
brush  deposits  a small  spot  of  ink,  the  image  being 
built  up  by  repeated  applications.  There  is,  however, 
a great  difference  in  the  textures  obtainable,  for  if  a 
stiff  ink  is  used  and  the  entire  surface  of  the  print  is 
worked  over  for  a long  time  these  minute  spots  of  ink 
are  spread  by  repeated  touches  of  the  brush  and  the 
final  result  will  have  a fine  texture.  If,  on  the  other 
hand,  a relatively  thin  ink  is  used,  so  that  the  desired 
gradations  are  rapidly  built  up,  the  texture  will  be 
coarse.  An  8X10  print  may  be  inked  up  to  full  con- 
trast in  ten  minutes  with  a thin  ink,  when  the  texture 

221 


TECHNIQUE  OF  OIL  AND  BROMOIL 


will  be  decidedly  coarse.  If  the  stiff  est  possible  ink  is 
used  with  a view  to  obtaining  a fine  texture  a print 
of  this  size  may  require  an  hour  or  more  for  complete 
inking. 

Although  it  is  possible  to  apply  a thin  ink  over  a 
stiff  one,  it  will  be  found  that  a stiff  ink  will  refuse  to 
adhere  over  a thin  one  unless  the  latter  has  first  been 
dried. 

It  is  possible  to  ink  a print  to  a certain  depth  and 
then  dry,  resoaking  and  completing  the  inking  at  a 
later  date,  but  the  writer  prefers  to  finish  a print  at  one 
sitting,  for  he  feels  that  by  this  method  the  best  results 
are  obtained,  the  effect  being  not  only  better  tech- 
nically but  being  also  freer  and  more  spontaneous 
from  an  artistic  point  of  view.  If  the  print  has  been 
dried  and  resoaked,  it  will  be  possible  to  apply  ink  by 
dabbing,  but  hopping  will  not  remove  any  of  the  first 
application. 

A new  brush  will  probably  shed  hairs  in  great 
profusion  on  the  print,  these  being  either  pulled  out  of 
the  brush  or  broken  off.  It  is  well  to  remove  each  hair 
as  soon  as  it  is  observed,  by  lifting  it  on  the  point  of  a 
needle  or  knife,  which  may  very  readily  be  done  with- 
out injury  to  the  print.  If  the  hairs  are  allowed  to 
accumulate  on  the  print  they  will  leave  marks  when 
working  over  them  and  these  marks  will  have  to  be 
spotted  out  in  the  finished  print.  After  two  or  three 
prints  have  been  inked,  the  brush  will  probably  cease 
to  shed  hairs,  or  at  all  events  will  lose  one  but  rarely. 

Drying  and  Degreasing. — When  the  print  is 
satisfactorily  inked  it  should  be  set  to  dry  and  should 
be  pinned  up  by  the  four  corners  in  a vertical  position, 

222 


GENERAL  REMARKS 


since  if  it  is  laid  horizontally  dust  will  settle  on  it  and  if 
the  corners  are  not  firmly  held  it  may  curl  up  and  crack 
when  straightened.  Drying  will  take  from  two  hours 
to  two  weeks,  depending  on  the  stiffness  of  the  ink 
and  on  the  amount  applied.  When  the  print  is  dry 
it  may  be  worked  on  freely  w7ith  a pencil  eraser  to 
lighten  values  or  ink  may  be  applied  to  a given  area 
with  the  brush,  though  it  must  be  remembered  that 
ink  will  adhere  to  the  dry  print  much  more  freely 
than  when  it  is  wet  and  that  it  will  adhere  uniformly 
over  the  entire  surface. 

The  finished  oil  print  has  always  a certain  lustre, 
this  being  due  to  the  medium  in  which  the  pigment  is 
ground.  Should  this  lustre  not  be  desired  it  may  be 
removed  by  soaking  the  print  for  about  fifteen  minutes 
in  gasoline,  and  this  soaking  should  take  place  as  soon 
as  the  ink  has  become  thoroughly  dried  and  not  until 
then,  for  if  it  is  done  too  soon  the  pigment  will  be 
removed  from  the  paper  and  if  it  is  left  too  long  the 
oily  medium  will  not  be  dissolved  from  the  ink. 

General  Remarks. — Any  one  who  has  followed 
the  foregoing  description  with  care  will  be  able  to 
induce  for  himself  the  cause  of  any  particular  failure, 
but  a few  general  indications  may  be  given. 

Over-printing  or  insufficient  soaking  will  give  too 
dark  a print,  but  these  faults  are  readily  differentiated, 
since  with  over-printing  and  proper  soaking  the  print 
will  have  the  proper  degree  of  contrast  and  the  margins 
will  remain  clear,  whereas  with  correct  exposure  and 
insufficient  soaking  the  print  will  be  flat  and  lacking 
in  contrast  and  the  margins  will  take  the  ink. 

The  effect  of  under-printing  is,  of  course,  obvious, 

223 


TECHNIQUE  OF  OIL  AND  BROMOIL 


and  excessive  soaking  may  cause  the  gelatine  of  the 
safe-edge  to  tear  under  the  brush  and  will  cause  the 
high  lights  of  the  picture  to  refuse  to  take  ink.  In 
extreme  cases  over-soaking  will  cause  tearing  of  the 
film  in  the  lights. 

Too  stiff  an  ink  will  refuse  to  adhere  to  the  lights 
and  too  thin  an  ink  will  adhere  too  readily,  the  former 
defect  being  seldom  found.  As  a corollary  to  this  it 
may  be  noted  that  a stiff  ink  gives  contrast,  whereas  a 
thin  ink  gives  flatness. 

Should  the  print  be  thickly  covered  with  fine  black 
specks,  this  is  probably  due  to  an  excessive  amount 
of  ink  on  the  brush,  and  the  latter  may  be  cleaned 
sufficiently  to  permit  of  continued  use  by  rubbing  on  a 
clean  cloth  or  piece  of  blotting  paper.  Should  the 
print  show  a number  of  small  white  spots,  these  are 
probably  due  to  the  brush  having  become  wet  through 
touching  the  blotting  papers,  and  if  it  cannot  be 
sufficiently  cleaned  on  a dry  cloth  it  must  be  washed 
out  and  allowed  to  dry  for  several  hours. 

The  brushes  should  be  cleaned  immediately  after 
use,  and  if  gasoline  is  used  the  brushes  will  probably 
be  dry  enough  to  use  in  an  hour  or  two,  but  if  they  are 
cleaned  with  soap  and  water  they  will  take  three  or 
four  times  as  long  to  dry.  They  should  be  dried  in  the 
paper  cones  in  which  they  are  kept,  or  the  hairs  may 
spread  and  the  brush  soon  become  useless. 

It  will  be  found  that  fixed-out  bromide  paper  has  a 
much  thicker  coating  of  gelatine  than  the  commercial 
oil  paper,  for  which  reason  it  permits  the  use  of  stronger 
negatives.  It  should  be  noted  that  if  a hypo  bath 
containing  alum  is  used  for  fixing  the  paper  will  prob- 

224 


THE  BROMIDE  PRINT 


ably  be  useless  for  oil  printing,  since  this  process 
depends  on  the  fact  of  the  gelatine  not  having  been 
tanned. 

Should  it  be  found  that  the  inking  is  not  proceeding 
satisfactorily,  the  print  may  be  cleaned  with  gasoline, 
dried  and  resoaked. 

Bromoil — The  Negative. — A negative  suitable  for 
use  with  the  bromoil  process  will  be  in  general  much 
softer  than  one  suitable  for  oil  printing,  though  this 
depends  somewhat  on  the  paper  used. 

The  Bromide  Print. — For  developing  the  bromide 
print  it  is  best  to  use  a developer  which  has  no  tendency 
to  tan  the  gelatine;  that  is,  amidol  or  dianol,  since  these 
work  without  the  use  of  an  alkali,  although  such  a 
developer  is  by  no  means  imperative.  The  print 
should  be  thoroughly  developed  so  that  all  the  light- 
affected  silver  is  reduced  to  the  metallic  state,  and  in 
order  to  secure  this  condition  development  should  be 
continued  for  two  or  three  minutes  after  the  print  has 
ceased  to  gain  strength.  Fixation  should  take  place  in 
a plain  hypo  bath,  for  if  a hardening  bath  is  used  it 
will  be  almost  impossible  to  swell  the  gelatine  suffi- 
ciently to  permit  of  inking.  The  writer  has  inked  a 
print  which  had  been  fixed  in  a hardening  hypo  bath  by 
giving  it  a prolonged  immersion  in  an  acid  solution  and 
soaking  in  water  at  about  150°  Fahrenheit,  but  this 
technique  is  not  recommended. 

The  bromide  print  should  be  by  no  means  a strong 
one,  for  if  the  shadows  approach  the  full  depth  possible 
to  the  bromide  process  it  will  be  difficult  to  obtain 
complete  rendering  of  the  shadow  detail  in  inking. 
It  should  be  borne  in  mind  that  softness  in  the  bromide 

15  225 


TECHNIQUE  OF  OIL  AND  BROMOIL 


print  will  not  interfere  with  the  obtaining  of  a full  rich 
black  in  the  finished  print,  since  ink  may  be  added  to 
practically  an  unlimited  extent. 

Bleaching. — The  purpose  of  the  bleaching  solu- 
tion is  to  tan  the  gelatine  by  reaction  between  the 
bleacher  and  the  silver  image,  and  there  are  formulae 
almost  innumerable  for  this  purpose,  different  workers 
having  their  especial  favorites.  The  writer  has  found 
the  following  two  formulae  to  be  thoroughly  satisfactory: 


Water 14  ounces 

Copper  sulphate  crystals 260  grains 

Potassium  bromide 260  grains 

Potassium  bichromate 48  grains 

Hydrochloric  acid  C.  P 30  minims 

Water 24  ounces 

Copper  sulphate  crystals 130  grains 

Sodium  chloride 720  grains 

Potassium  bichromate 10  to  50  grains 


Increasing  the  amount  of  potassium  bichromate  in- 
creases the  tanning  action,  and  the  worker  should 
experiment  for  himself  with  the  paper  he  wishes  to 
use,  since  different  papers  require  different  treatments. 
If  the  bleacher  is  used  warm  (up  to  100°  Fahrenheit) 
greater  relief  is  obtained,  and  this  is  sometimes  neces- 
sary in  the  case  of  a hard  gelatine.  A gelatine  which 
is  so  hard  as  not  to  respond  to  the  use  of  a warm 
bleacher  and  hot  water  for  soaking  may  often  be 
improved  by  soaking  for  a few  minutes  in  a 3 per  cent, 
solution  of  sulphuric  acid  C.  P.,  which  also  may  be 
used  warm.  The  acid  bath,  however,  will  rarely  be 
necessary  if  the  print  is  of  the  proper  quality  and 
has  been  fixed  in  plain  hypo.  The  bleacher  given  above 
keeps  well  and  may  be  used  repeatedly,  but  it  is 
226 


TRANSFERRING 


generally  preferable  to  make  it  up  fresh  for  each  batch 
of  prints,  since  more  uniform  results  are  thus  obtained. 
The  fixed  and  washed  print  is  immersed  in  the  bleacher 
until  no  further  action  is  observed,  although  the  image 
will  not  be  entirely  removed.  It  is  then  washed  in 
running  water  until  free  from  bleacher,  when  it  may 
either  be  inked  or  may  be  dried  and  reserved  for  future 
inking.  Drying  is  not  imperative,  but  better  results  are 
obtained  if  it  is  done,  since  the  full  tanning  action  of 
the  bleacher  is  not  secured  otherwise.  Of  course,  a 
number  of  prints  may  be  bleached  at  a time  and  kept, 
but  it  is  not  advisable  to  postpone  inking  for  more  than 
a few  weeks  at  most,  though  bleached  prints  have  been 
successfully  inked  six  months  after  treatment.  It  is  well 
to  fix  the  print  in  a plain  hypo  bath  after  bleaching. 

Subsequent  Treatment. — The  subsequent  tech- 
nique of  the  printing,  that  is,  the  operations  of  soaking, 
inking,  drying  and  degreasing,  is  identical  with  that 
used  in  the  case  of  oil  printing. 

Transferring.— Transferring  is  simply  a matter 
of  placing  the  oil  or  bromoil  print  in  contact  with  a 
sheet  of  comparatively  absorbent  paper,  that  is,  a 
paper  which  is  not  too  heavily  sized,  and  running  the  two 
together  through  a press  such  as  an  etching  press  or  a 
clothes  wringer.  Almost  any  charcoal  paper  will  work 
satisfactorily,  and  many  other  papers  will  be  found 
useful,  although  the  Japanese  vellums  and  tissues  are 
so  soft  in  texture  that  the  fibres  are  likely  to  adhere 
to  the  original  and  the  transfer  paper  will  be  roughened 
in  places  when  the  two  are  separated.  With  care, 
however,  very  beautiful  results  may  be  obtained  with 
such  papers. 


227 


TECHNIQUE  OF  OIL  AND  BROMOIL 


If  it  is  intended  to  transfer,  the  oil  or  bromoil  print 
should  be  inked  with  a comparatively  thin  ink,  since 
a stiff  ink  will  not  adhere  satisfactorily  to  the  transfer 
paper.  The  use  of  a thin  ink,  as  has  been  stated  above, 
causes  a granular  appearance  in  the  oil  or  bromoil 
print,  but  the  operation  of  transferring  modifies  this  to 
a great  extent  by  spreading  out  the  small  spots  of  ink, 
thus  giving  a texture  approaching  the  close  texture 
resulting  from  the  use  of  a stiff  ink  in  straight  oil  or 
bromoil  work.  The  outlines  will  not,  however,  assume 
the  distinctness  of  those  in  an  oil  or  bromoil  which  has 
been  inked  with  a stiff  ink.  One  of  the  ablest  of  the 
English  workers  in  this  medium  told  the  writer  that 
he  uses  the  original  bromide  or  oil  print  simply  as  an 
indication  of  the  outlines,  relying  almost  entirely  on 
the  brush  action  for  securing  the  desired  values,  and 
stating  that  the  ink  employed  is  so  thin  that  a 12  X 15 
print  is  fully  inked  in  ten  or  fifteen  minutes.  Rapid 
working  is  far  more  necessary  if  the  print  is  to  be 
transferred  than  otherwise 

In  order  to  prevent  the  print  from  sticking  to  the 
transfer  paper  it  is  sometimes  advised  to  give  the 
former,  prior  to  soaking,  an  immersion  of  two  minutes 
in  a 1 per  cent,  formaldehyde  solution,  but  the  neces- 
sity for  the  formaldehyde  bath  may  be  avoided  by 
allowing  the  water  to  dry  out  of  the  film  slightly  before 
transferring,  the  water  drying  out  so  much  more  rapidly 
than  the  medium  in  which  the  ink  is  ground.  A fairly 
heavy  pressure  should  be  used,  although  it  is  impossible 
to  give  any  definite  information  on  this  point,  since 
the  pressure  necessary  will  vary  with  the  stiffness  of 
the  ink,  with  the  quality  of  the  transfer  paper  and 
228 


TRANSFERRING 


with  the  result  desired.  The  transferred  print  will  of 
course  be  reversed  as  regards  right  and  left  and  allow- 
ance must  be  made  for  this  in  printing  the  original 
oil  or  bromoil  if  it  is  imperative  that  the  completed 
picture  be  the  right  way  around.  If  a clothes  wringer 
is  used  the  oil  or  bromoil  print  should  be  supported 
on  a flat  board  or  piece  of  sheet  metal,  and  two  or 
three  pieces  of  blotting  paper  or  of  etcher’s  blankets 
should  be  placed  over  the  transfer  paper  whether  the 
clothes  wringer  or  the  etching  press  is  used,  since  if 
this  is  not  done  uneven  pressure  may  result,  causing 
the  ink  to  transfer  more  heavily  in  some  portions  of 
the  picture  than  in  others. 

Most  writers  lay  special  emphasis  on  the  fact  that 
it  is  possible  to  modify  relative  values  to  an  unlimited 
extent  in  oil  or  bromoil  work,  and  this  fact  is  obviously 
of  primary  importance,  it  being  seldom  the  case  that 
a direct  transcript  from  nature  is  artistically  satis- 
factory, but  in  the  author’s  opinion  the  fundamental 
value  of  these  processes  is  found  in  a deeper  psychic 
quality  than  this.  It  is  well  known  that  the  chief 
value  of  any  graphic  art,  and  even  of  the  crafts,  depends 
on  the  fluent  and  irregular  action  of  the  hand,  the  very 
precision  of  mechanical  carving,  for  example,  operating 
to  render  it  uninteresting  when  compared  with  hand 
work.  Photographers  have  felt  this  mechanical  quality 
in  the  productions  of  the  camera,  and  have  endeavored 
to  avoid  it  by  brush-development  of  gum  prints,  by 
etching  on  the  negative,  and  by  other  devices,  but 
these  are  not  satisfactory  solutions  of  the  problem, 
the  results  showing  their  hybrid  character  and,  further, 
losing  the  greatest  advantage  of  photography,  the  per- 

229 


TECHNIQUE  OF  OIL  AND  BROMOIL 


feet  rendition  of  outlines  and  gradations.  Thus,  in 
platinum,  gum-platinum,  and  most  other  mediums  we 
have  either  a print  compounded  of  photography  and 
hand- work — always  an  abomination  — or  one  in  which, 
beautiful  though  it  may  be  in  outline,  gradation  and 
tone,  we  always  feel  the  machine,  and  the  effect  can 
never  reach  the  highest  pitch  of  artistic  expression. 
The  worker  in  oil,  however,  has  at  his  disposal  a medium 
in  which  he  can  render  perfectly  the  imperceptible  gra- 
dations of  light  on  surfaces  and  the  precise  outlines  of 
the  subject,  or  can  vary  at  will  either  outlines  or  gra- 
dations, all  without  losing  the  beauty  of  the  photo- 
graphic image,  and,  in  addition,  can  by  skilful  manip- 
ulation of  the  brush  and  the  ink  vary  the  texture  of 
the  image  in  different  parts  of  the  print.  A platinum 
print  may  be  very  beautiful,  but  it  remains  fundamen- 
tally a product  of  a machine,  whereas  an  oil  print 
necessarily  possesses,  to  a greater  or  less  degree, 
depending  on  the  skill  and  feeling  of  the  worker,  the 
personal  touch  so  prized  by  artists  and  art  lovers, 
and  may  be  so  imbued  with  the  personality  of  its 
maker  as  to  rise  to  the  very  highest  levels  of  graphic  art. 


A SIGN  SHADOW,  CHESTER 
BY  CHARLES  KENDALL 
From  a Bromoil  Transfer 


CHAPTER  XV 


TECHNIQUE  OF  PHOTOGRAVURE 

Theory. — A smooth  copper  plate  is  burnished  and 
thoroughly  cleaned  and  is  covered  with  a fine  dust  of 
asphaltum  powder,  which  is  caused  to  adhere  to  the 
plate  by  heat.  A carbon  print  is  then  made  from  a 
glass  positive  and  transferred  to  the  grained  copper 
plate,  stripped  and  developed.  After  the  carbon  print 
is  dry,  the  plate  is  immersed  in  a bath  of  perchloride  of 
iron,  which  possesses  the  property  of  dissolving  copper. 
Since  the  carbon  print  consists  of  varying  thicknesses 
of  gelatine,  the  etching  bath  penetrates  this  film  and 
attacks  the  copper  under  the  thinnest  portions  of  the 
film  first,  then  under  the  next  thicker  and  so  on  until 
it  has  etched  the  copper  to  a satisfactory  depth  under 
the  thickest  portions  of  the  carbon  print.  Since  the 
carbon  print  was  made  from  a positive  it  follows  that 
the  print  itself  is  a negative  and  the  thinnest  portions 
are  in  the  shadows  of  the  picture,  consequently  the 
copper  is  etched  deeper  in  the  shadows  than  in  the  half 
tones  and  deeper  here  than  in  the  lights.  Also,  the 
copper  is  etched  only  where  it  was  not  protected  by  the 
grains  of  asphaltum  powder,  so  that  the  final  result 
after  cleaning  off  the  gelatine  film  and  the  asphaltum 
dust  is  a copper  plate  etched  deeply  in  the  shadows, 
less  deeply  in  the  half  tones  and  least  of  all  in  the  lights, 
but  having  only  a certain  proportion  of  its  surface 
etched.  This  plate  is  then  inked  with  an  oily  ink 
which  is  worked  well  into  the  little  depressions  made 

231 


TECHNIQUE  OF  PHOTOGRAVURE 


by  the  etching  fluid,  and  the  surface  is  wiped  with 
cloths  and  with  the  edge  of  the  hand  so  as  to  remove 
all  the  ink  from  the  surface,  leaving  that  which  is  held 
in  the  little  hollows.  A sheet  of  paper  is  then  laid  in 
contact  with  the  copper  plate  and  pressure  is  applied 
to  it.  The  result  is  that  the  paper  is  forced  into  the 
little  depressions  of  copper  and  lifts  the  ink  out,  and 
since  there  was  more  ink  in  the  shadows  than  in  the 
half-tones — the  former  being  more  deeply  etched — 
and  more  here  than  in  the  lights,  a positive  print  is 
produced. 

The  Copper  Plate. — This  should  be  of  the  best 
grade  of  copper  and  should  be  bought  already  smoothed, 
burnished  and  bevelled,  since  although  the  worker  can 
prepare  the  plate  for  himself,  it  involves  too  great  an 
expenditure  of  time  and  effort  to  be  worth  while.  The 
bevelling  is  not  necessary  unless  the  print  is  to  be  on  a 
sheet  of  paper  larger  than  the  plate,  in  which  case  the 
paper  will  probably  be  cut  unless  the  plate  is  bevelled. 
The  plate  should  be  approximately  one-eighth  inch 
thick  for  prints  8X10  inches,  although  lighter  plates 
may  be  used  for  smaller  prints.  The  surface  should 
be  examined  to  make  sure  that  it  is  free  from  scratches 
or  pits,  since  these,  unless  occurring  in  the  shadows  of 
the  picture,  will  show  in  the  finished  print  by  reason  of 
their  catching  and  holding  the  ink.  The  plate  should 
be  cleaned  with  a solution  of  caustic  soda  or  caustic 
potash  to  remove  the  grease  and  rinsed,  after  which  it 
is  cleaned  with  a dilute  solution  of  sulphuric  acid  to 
remove  the  tarnish.  These  solutions  are  rubbed  on  the 
plate  with  a tuft  of  cotton,  and  rubber  gloves  should 
be  worn  during  the  operation.  The  plate  is  rinsed  after 

232 


LAYING  THE  GROUND 


the  treatment  with  acid  and  is  then  polished  with  Bon 
Ami  applied  in  the  same  manner.  After  the  cleaning 
it  is  rinsed  and  stood  up  to  dry. 

Laying  the  Ground. — There  are  two  methods  of 
graining  the  plate,  which  are  described  below.  The 
second  is  of  comparatively  recent  development  and  in 
the  writer’s  opinion  is  to  be  preferred  to  the  other. 
For  the  first  method  a dusting  box  should  be  used,  this 
being  shown  in  Figure  44,  the  dimensions  given  being 
sufficient  for  plates  up  to  10X12  inches.  Into  this  box 
is  placed  about  one  pint  of  finely  ground  asphaltum 


Fig.  44. 

powder.  The  door  is  fastened  on,  and  the  box  is  rotated 
several  times,  the  top,  sides  and  bottom  being  beaten 
with  the  hand  as  the  box  is  turned  around  in  order  that 
any  particles  of  asphaltum  which  would  otherwise  ad- 
here to  the  inside  of  the  box  may  be  dislodged.  The 
box  is  brought  to  rest  and  bolted  to  hold  it  steady. 
The  door  is  then  opened  and  the  copper  plate  is  care- 
fully introduced.  The  copper  plate  should  be  supported 
an  inch  or  more  above  the  bottom  of  the  dusting  box, 
an  empty  plate  box  serving  to  accomplish  this,  for  should 
the  plate  simply  be  placed  in  the  box  and  the  dust 

233 


TECHNIQUE  OF  PHOTOGRAVURE 


allowed  to  settle  on  it,  it  will  probably  be  found  on  re- 
moving the  plate  that  the  dust  has  settled  irregularly 
about  the  edges,  this  effect  being  explained  as  resulting 
from  air  currents  set  up  within  the  box  by  the  falling 
dust.  This  irregularity  may  be  avoided  by  placing  the 
plate  on  a sheet  of  glass  an  inch  or  so  larger  all  around 
than  the  plate  itself,  when  the  irregularities  will  be  on 
the  glass  instead  of  on  the  copper.  The  character  of 
the  ground  depends  to  a considerable  extent  on  the 
length  of  time  that  the  box  is  allowed  to  rest  before 
inserting  the  plate,  and  also  on  the  length  of  time  the 
plate  remains  in  the  box,  since  the  coarser  particles  of 
dust  naturally  fall  first,  being  followed  by  the  finer 
ones.  For  a coarse  ground  the  box  may  be  allowed  to 
rest  for  about  twenty  seconds  before  inserting  the 
plate,  and  the  plate  may  be  allowed  to  remain  in  the 
box  for  four  or  five  minutes.  If  a finer  ground  is 
desired  the  box  may  rest  for  one  or  one  and  a half 
minutes  before  the  plate  is  inserted,  but  in  this  case 
so  much  of  the  dust  will  have  settled  that  it  may  be 
necessary  to  insert  the  plate  three  or  four  times.  The 
quality  of  the  ground  should  be  varied  to  some  extent 
according  to  the  character  of  the  print  desired,  for  if  a 
fine  ground  is  used  it  will  not  be  feasible  to  produce  a 
print  with  strong  shadows,  since  the  deep  etching 
required  would  cause  undermining  of  the  little  points 
of  copper,  and  the  shadows  would  fail  to  hold  the  ink 
properly.  After  the  plate  has  remained  in  the  box  for 
the  determined  length  of  time  it  should  be  removed 
very  carefully,  as  a jar  or  a breath  of  air  will  suffice  to 
scatter  the  dust.  The  plate  when  examined  should  have 
the  appearance  of  a fine  cloth  and  the  texture  of  the 
234 


LAYING  THE  GROUND 


ground  should  be  uniform.  Any  large  particles  which 
may  have  fallen  on  the  plate  may  be  removed  with  a very 
fine -pointed  brush  slightly  moistened  with  water.  Should 
the  appearance  of  the  plate  be  unsatisfactory  the  dust 
may  be  wiped  off  with  a tuft  of  cotton  and  another 
ground  may  be  laid.  When  a satisfactory  ground  has 
been  obtained  the  plate  is  grasped  at  one  end  in  a small 
hand  vise  or  pair  of  pliers,  a slip  of  cardboard  being 
bent  over  the  edge  of  the  plate  in  order  to  prevent  in- 
jury to  the  copper.  The  plate  is  then  held  over  a Bun- 
sen burner  or  an  ordinary  gas  stove  and  moved  about 
until  the  ground  is  set.  The  setting  of  the  ground  may 
be  determined  by  the  fact  of  the  dust  first  losing  its 
dull  appearance  and  becoming  transparent,  and  after- 
ward assuming  a blue  color.  If  too  much  heat  is  applied 
the  dust  may  be  melted  and  caused  to  run  together, 
forming  a uniform  varnish  over  the  entire  surface  of 
the  plate,  but  the  heat  required  to  effect  this  with 
asphaltum  is  so  great  that  there  is  little  danger  of  such 
an  occurrence,  it  being  more  likely  to  take  place  if 
rosin  or  copal  is  used,  as  is  sometimes  done.  After 
cooling,  the  plate  may  be  examined  with  a magnifying 
glass  and  if  the  ground  is  considered  insufficient  another 
may  be  laid  over  the  first  and  set  in  the  same  manner. 

The  alternative  method  is  to  dispense  entirely  with 
dusting  and  to  use  instead  a screen  especially  made  for 
photogravure  and  somewhat  resembling  a half-tone 
screen.  The  carbon  tissue  is  exposed  under  the  positive 
and  is  then  placed  in  contact  with  this  screen  under 
heavy  pressure — a printing  frame  with  pressure  screws 
should  be  employed — and  is  then  exposed  to  the  same 
printing  light  for  about  half  as  long  as  was  required  to 

235 


TECHNIQUE  OF  PHOTOGRAVURE 


print  from  the  positive.  The  tissue  is  then  transferred 
to  a polished  copper  plate,  stripped  and  developed  in 
the  usual  manner,  when  the  gelatine  film  will  consist 
of  a series  of  fine  lines  with  the  gradations  of  the  positive 
superposed  on  them,  these  lines  of  insoluble  gelatine 
serving  to  protect  the  copper  from  the  etching  bath  in 
precisely  the  same  manner  as  the  grains  of  asphalt um. 
As  has  been  said,  the  writer  prefers  this  method  to  the 
other,  since  it  is  more  rapid  and  more  certain,  the  sole 
drawback  being  the  cost  of  the  screen,  which,  however, 
with  ordinary  care  will  keep  in  good  condition  in- 
definitely. 

It  is  also  possible  to  lay  a ground  by  flowing  the 
plate  with  a solution  of  rosin  in  absolute  alcohol  or  by 
spraying  this  solution  on  from  an  atomizer.  The 
writer  has  never  used  a liquid  ground,  and  it  is  not  in 
general  recommended.  One  of  the  ablest  of  present 
workers  has  said:  “I  have  found  liquid  grounds  to  be 
troublesome  and  unsatisfactory.” 

The  Positive. — This  may  be  made  on  a dry  plate 
either  by  contact  printing  or  by  enlarging,  and  should 
have  only  a moderate  degree  of  vigor,  for  if  the  positive 
is  too  strong  the  carbon  resist  will  be  as  well  and  the 
plate  will  be  over-etched  in  the  shadows.  In  extreme 
cases  this  over-etching  may  be  so  great  as  to  cause 
under-cutting  of  the  copper  where  protected  by  the 
grains  of  asphaltum,  so  that  the  little  hills  of  copper  will 
break  down  and  the  shadows  will  have  less  depth  than 
they  should.  It  is  also  possible  to  make  the  positive 
by  contact  printing  in  carbon,  transferring  the  carbon 
tissue  to  a piece  of  ground  glass  as  indicated  in  the  chap- 
ter on  carbon  printing.  The  transparency  must  be 

236 


THE  RESIST 


provided  with  a safe-edge  as  in  ordinary  carbon  work 
and  any  modification  of  relative  values  which  may  be 
desired  should  be  made  either  on  the  negative  or  on 
the  positive,  since  it  is  difficult  to  do  any  handwork  on 
the  copper  plate  or  on  the  resist  without  such  hand- 
work being  apparent. 

The  Resist. — The  carbon  print  which  is  made  from 
the  positive  and  is  developed  on  the  copper  plate  is 
known  as  the  resist,  and  a special  tissue  is  provided  for 
this  purpose,  the  ordinary  tissues  being  less  suitable, 
although  they  may  be  used  in  an  emergency.  The 
tissue  for  the  resist  may  be  obtained  in  a bright  red, 
a dark  red,  or  a brown,  the  difference  being  that  the 
lighter  color  makes  it  easier  to  watch  the  process  of 
etching,  whereas  with  the  darker  tissue  it  is  easier  to 
watch  development  of  the  resist.  The  writer  prefers 
to  use  the  lightest  tissue,  developing  one  print  on  a 
sheet  of  ground  glass  and  modifying  the  time  of  print- 
ing or  the  temperature  of  the  developing  water  for  the 
resist,  as  may  be  indicated  by  the  result  first  obtained. 

The  tissues  may  be  sensitized  by  immersion  in  the 
bath  for  which  a formula  was  given  in  the  chapter  on 
carbon  printing  and  should  be  squeegeed  to  a ferrotype 
plate  and  allowed  to  dry  in  the  dark,  and  the  use  of  a 
ferrotype  plate  is  of  greater  importance  than  for  or- 
dinary carbon  work,  it  being  imperative  to  keep  the 
resist  free  from  dust. 

The  writer  times  the  printing  of  the  resist  by  making 
a normal  P.  O.  P.  proof  from  the  positive  and  printing 
the  resist  for  the  length  of  time  required  for  proofing. 

When  the  resist  is  printed  it  is  transferred  to  the 
copper  plate  precisely  as  though  the  latter  were  a sheet 

237 


TECHNIQUE  OF  PHOTOGRAVURE 


of  transfer  paper  and  if  the  work  is  properly  done  adhe- 
sion will  be  perfect,  even  though  transferring  is  done 
directly  on  the  burnished  copper,  as  is  the  case  when  the 
screen  is  used.  The  backing  is  stripped  off  and  the 
resist  is  developed  as  in  the  case  of  an  ordinary 
carbon  print,  though  every  effort  should  be  made  to 
attain  such  accuracy  of  printing  that  the  print  may  be 
properly  developed  at  a temperature  not  exceeding  120° 
Fahrenheit  or  the  film  may  strip  off  the  copper  when 
dried.  The  resist  should  be  printed  and  developed  in 
such  a manner  that  the  thinnest  possible  film  of  gelatine 
will  remain  on  the  copper  in  the  shadows,  without, 
however,  losing  any  of  the  shadow  detail,  and  it  is  for 
this  reason  that  the  writer  prints  a test  sheet  and  devel- 
ops it  on  ground  glass,  keeping  a record  of  the  tempera- 
ture of  the  developing  water.  Care  should  be  used  to 
see  that  no  particles  of  dust  get  between  the  copper 
plate  and  the  resist  or  adhere  to  the  resist  while  it  is  dry- 
ing, since  such  particles  will  probably  cause  spots  in 
the  finished  print.  Drying  of  the  developed  resist 
should  preferably  be  spontaneous  and  in  reasonably 
good  atmospheric  conditions  will  be  complete  in  the 
course  of  an  hour  or  so,  though  if  time  is  of  importance 
the  plate  may  be  flowed  two  or  three  times  with  a 50 
per  cent,  solution  of  alcohol  in  water,  then  two  or  three 
times  with  a 75  per  cent,  solution  and  may  finally  be 
immersed  for  two  or  three  minutes  in  pure  alcohol. 
After  this  treatment  drying  will  take  place  very  rapidly, 
but  there  is  greater  danger  of  the  film  stripping  from  the 
copper  than  if  the  drying  is  spontaneous.  When  the  re- 
sist is  dried  the  edges  and  back  of  the  copper  plate  should 
be  protected  by  means  of  asphaltum  varnish  thinned 
238 


ETCHING  THE  PLATE 


with  benzole,  which  may  be  applied  around  the  edges 
of  the  resist  with  a fine  ruling  pen,  a brush  then  being 
used  to  work  up  to  this  line  and  over  the  portion  to  be 
varnished.  The  varnish  will  dry  in  the  course  of  two 
or  three  minutes  and  the  plate  is  then  ready  for  etching. 

Etching  the  Plate. — If  a single  solution  of  per- 
chloride  of  iron  were  to  be  used  for  etching  it  would  pen- 
etrate the  gelatine  film  so  rapidly  that  the  copper  would 
be  attacked  in  the  high  lights  of  the  picture  before  it 
was  deeply  enough  etched  in  the  shadows,  and  although 
a single  solution  is  sometimes  used  in  the  case  of  line 
work  it  is  not  satisfactory  when  a full  scale  of  grada- 
tions is  desired,  and  the  process  must  in  that  case  be 
modified  somewhat. 

It  is  a property  of  perchloride  of  iron  that  a strong 
solution  of  it  will  not  penetrate  a thick  gelatine  film, 
and  advantage  is  taken  of  this  circumstance  in  photo- 
gravure work.  A fairly  strong  solution  is  used  at  first 
and  this  penetrates  the  thinnest  portions  of  the  resist, 
etching  the  copper  under  them,  but  does  not  penetrate 
the  thicker  parts.  When  this  action  has  proceeded  as 
far  as  it  will — that  is,  has  gone  through  the  thickest 
film  which  it  can  penetrate — a weaker  solution  is 
applied  and  this  penetrates  the  next  thicker  portion 
of  the  film,  etching  the  copper  under  this,  and  at  the 
same  time  continues  the  etching  in  the  shadows.  A 
still  weaker  solution  is  then  used  and  this  extends  the 
action  still  further  and  so  on,  until  the  weakest  solution 
has  penetrated  the  thickest  portion  of  the  resist  and 
has  acted  on  the  copper  to  the  proper  extent.  Thus 
each  solution  intensifies  the  action  which  has  already 
been  begun  and  starts  etching  in  gradations  lighter  than 

239 


TECHNIQUE  OF  PHOTOGRAVURE 


those  attacked  by  the  preceding  solution.  Different 
writers  recommend  different  numbers  of  etching  baths, 
Herbert  Denison  advising  six  baths  of  the  following 
strengths,  the  density  being  measured  with  a Beaume 
hydrometer  designed  for  heavy  liquids:  45°,  43°,  40°, 
38°,  36°,  and  33°.  Other  writers  say  that  a good  general 
series  is:  40°,  36°,  33°,  and  30°.  The  range  of  density 
of  the  solutions  depends  on  the  result  desired  and  on 
the  quality  of  the  transparency  and  the  resist,  since  a 
resist  having  considerable  density  will  require  a weaker 
series  than  a thinner  one,  and  a resist  having  little 
contrast  will  require  a greater  number  of  solutions  than 
a stronger  one,  for  obviously  the  greater  the  number  of 
solutions  applied  the  greater  will  be  the  contrast  in  the 
finished  print. 

To  make  the  etching  baths,  take  7 pounds  of  per- 
chloride  of  iron  crystals,  add  60  ounces  of  water  and  dis- 
solve by  gentle  heat.  Take  10  ounces  of  this  solution 
and  add  stronger  ammonia,  a little  at  a time,  until  the 
solution  becomes  thick,  then  add  this  to  the  bulk  of 
the  solution  and  boil  to  expel  the  excess  of  ammonia. 
Allow  this  to  stand  for  twenty-four  hours,  bring  to  a 
temperature  of  70°  Fahrenheit,  and  test  it  with  the 
hydrometer.  Should  it  not  test  45°  it  may  be  boiled 
until  it  does  so,  the  testing  in  each  case  being  done  at 
the  temperature  indicated.  When  it  tests  45°  Beaum6 
a portion  is  bottled  and  labeled.  The  stock  solution  is 
then  diluted  with  water  at  70°  Fahrenheit  (if  cold  water 
is  used  the  perchloride  may  be  precipitated)  until  the 
next  weaker  step  is  reached,  when  a further  portion  is 
bottled  off,  and  so  on  until  the  complete  range  of  solu- 
tions has  been  obtained.  This  will  make  about  16 

240 


ETCHING  THE  PLATE 


ounces  each  of  the  six  baths  indicated  above.  It  will 
be  found  that  when  this  has  stood  for  a time  a sedi- 
ment will  form  and  the  clear  solution  may  be  decanted 
or  siphoned  off.  These  baths  improve  with  use  and  it 
is  advised  that  a piece  of  copper  wire  be  suspended  in 
each  of  the  bottles  and  allowed  to  remain  for  about 
fifteen  minutes  before  they  are  used  for  the  first 
time. 

It  will  be  found  convenient  to  have  six  trays  of 
porcelain,  glass,  or  hard  rubber,  and  to  place  the  six 
solutions  in  these  in  regular  order.  The  plate  with  the 
resist  mounted  on  it  is  lightly  dusted  and  placed  in  the 
strongest  solution,  the  tray  being  rocked  and  the  plate 
watched  carefully.  If  the  resist  is  too  thick  this  solu- 
tion may  not  penetrate  the  shadows  at  all  and  after 
three  or  four  minutes  the  plate  is  lifted  out,  drained 
and  placed  in  the  next  tray.  If,  on  the  other  hand,  the 
strongest  solution  penetrates  the  film — which  it  will  do 
if  printing  and  development  have  been  correct — the 
copper  will  be  seen  to  discolor,  and  if  the  red  tissue  is 
used  for  the  resist  there  will  be  no  difficulty  at  all  in 
observing  the  action.  This  discoloration  will  be  seen 
to  spread  over  the  surface  of  the  plate,  which  should 
be  allowed  to  remain  in  the  solution  until  the  discolora- 
tion has  ceased  to  spread.  When  the  discoloration  has 
ceased  spreading  in  each  solution  the  plate  is  drained 
and  transferred  to  the  next  weaker  bath,  where  it  re- 
mains until  the  time  for  its  removal.  It  should  be 
allowed  to  remain  in  the  weakest  solution  necessary 
until  the  high  lights  have  been  completely  discolored, 
when  it  is  rinsed  rapidly  in  hot  running  water  and  the 
softened  resist  is  rubbed  off  with  a tuft  of  cotton.  The 

16  241 


TECHNIQUE  OF  PHOTOGRAVURE 


asphaltum  ground,  if  such  was  used,  together  with  the 
varnish  on  the  edges  of  the  plate,  may  be  removed 
with  benzole  and  the  plate  is  then  cleaned  with  Bon 
Ami,  after  which  it  is  rinsed  in  hot  water  and  dried 
and  is  then  ready  for  printing. 

Great  control  over  the  finished  result  is  possible 
through  variations  in  the  etching  baths,  for,  as  has 
already  been  indicated,  a greater  number  of  baths 
gives  greater  contrast,  and  if  a soft  result  is  desired 
etching  may  be  commenced  in  a weaker  bath  than  45°, 
so  that  the  number  of  baths  is  shortened. 

If  the  resist  is  too  dense  it  may  be  that  the  weakest 
bath  will  not  penetrate  the  thickest  portions  of  the 
resist  and  in  that  case  the  33°  solution  may  be  diluted 
still  further. 

Printing. — The  ink  used  for  printing  is  that  reg- 
ularly supplied  for  photogravure  work  and  may  be  of 
any  desired  color.  It  will  have  greater  brilliance  and 
richness  if  freshly  ground,  but  for  all  practical  pur- 
poses it  will  work  satisfactorily  if  purchased  in  a collaps- 
ible metal  tube  from  which  the  required  amount  may 
be  squeezed  as  it  is  needed.  Boiled  linseed  oil  may  be 
used  for  thinning  the  ink,  which  should  ordinarily, 
when  ready  for  use,  have  such  consistency  that  when  a 
small  portion  is  lifted  on  the  palette  knife  it  can  be 
prevented  from  falling  off  only  by  turning  the  knife 
around.  A stiff  ink  will  give  a darker  print  than  a thin 
one,  hence  it  follows  that  considerable  modification  of 
result  is  possible  through  varying  the  consistency  of 
the  ink. 

To  apply  the  ink  to  the  plate,  a dabber  will  be  re- 
quired, and  this  may  either  be  purchased  from  a dealer 

242 


PRINTING 


in  photogravure  supplies  or  may  be  made  as  follows: 
A strip  of  heavy  woolen  cloth  about  six  inches  wide 
and  perhaps  three  feet  long  has  V shaped  notches  cut 
in  one  edge  every  few  inches.  The  cloth  is  then  wound 
up  until  the  base  is  three  or  four  inches  in  diameter, 
when  the  end  is  stitched  fast.  A cord  is  then  wound 
around  the  neck  of  the  dabber,  the  final  shape  of  the 
instrument  somewhat  resembling  that  of  a pestle.  The 
base  of  the  dabber  may  be  sliced  off  with  a sharp  knife 
until  it  is  even,  and  a piece  of  the  same  cloth  is  stretched 
over  it  and  carried  up  the  sides,  being  stitched  in  place. 
With  continued  use  this  covering  will  become  stiff  with 
old  ink  and  may  be  replaced  when  necessary  . 

The  ink  is  spread  in  a film  on  a sheet  of  glass  or  a 
palette  and  the  dabber  is  pressed  into  it  several  times 
to  insure  its  being  thoroughly  covered  with  the  ink. 
The  plate  is  then  warmed  over  a gas  flame  until  it  is 
about  as  warm  as  the  hand  can  bear  and  the  dabber  is 
worked  back  and  forth  over  the  surface  with  a rocking 
motion,  in  all  directions,  until  the  depressions  in  the 
copper  are  thoroughly  filled  with  ink.  A piece  of  coarse 
well-washed  muslin  about  two  feet  square  is  then 
wadded  up  in  the  form  of  a ball  and  the  surface  ink  is 
wiped  off  the  plate  with  it,  this  being  followed  by  wiping 
with  a finer  piece  of  cloth.  The  wiping  muslin  should 
be  folded  in  such  a manner  as  to  present  a smooth 
surface  to  the  plate,  and  when  the  plate  has  been  wiped 
thoroughly  with  the  cloth,  wiping  is  finished  with  the 
edge  of  the  hand.  Wiping  in  this  manner  will  leave  a 
slight  tint  over  the  entire  plate,  and  should  this  not 
be  desired  the  hand  may  be  rubbed  on  a cake  of  Bon 
Ami  and  lightly  wiped  with  a cloth  and  then  be  passed 

243 


TECHNIQUE  OF  PHOTOGRAVURE 


over  the  plate,  when  the  surface  ink  is  thoroughly  re- 
moved and  the  plate  yields  what  is  called  a “natural” 
print.  After  wiping,  the  margins  of  the  plate  may  be 
cleaned  with  a piece  of  chamois  folded  over  the  finger, 
and  the  plate  is  ready  for  printing.  It  will  be  found  that 
the  plate  has  become  cool  by  this  time  and  will  give  a 
darker  print  than  if  it  is  kept  warm  during  wiping,  the 
ink  being  thinner  when  warm,  so  that  more  is  removed 
by  the  cloth.  The  use  of  a soft  rag,  greater  pressure  or 
slow  wiping  will  give  a lighter  print  than  the  reverse 
treatment,  and  considerable  modification  is  possible 
by  varying  the  treatment  in  these  respects. 

For  printing,  the  etching  press  is  advised,  although 
if  it  is  not  desired  to  spend  the  amount  of  money 
necessary  for  such  a piece  of  apparatus,  a clothes- 
wringer  may  be  used,  but  it  will  not  be  possible  to 
make  such  large  prints  with  this  as  with  the  regular 
press.  The  etching  press  is  furnished  with  a metal 
bed-plate  which  travels  between  two  rollers,  and  if  a 
clothes  wringer  is  employed  it  will  be  necessary  to  have 
a flat  piece  of  stout  wood  or  metal  on  which  to  rest  the 
plate  during  its  passage  between  the  rollers.  If  the 
etching  press  is  used  the  plate  is  laid  on  a sheet  of  zinc 
or  paper  which  rests  on  the  bed  plate,  the  paper  to  be 
printed  on  is  placed  on  the  plate  and  several  pieces  of 
etcher’s  blanket  are  laid  over  the  paper.  The  screws 
of  the  press  are  then  screwed  down  to  the  proper  point 
and  the  press  is  revolved  by  means  of  the  handle.  When 
the  plate  has  passed  through  the  rolls  the  blankets  are 
lifted  and  the  paper  may  be  removed  from  the  plate. 
It  is  impossible  to  give  any  definite  idea  as  to  the  pres- 
sure required,  but  it  should,  roughly  speaking,  be  so 

244 


MODIFICATIONS 


great  that  considerable  force  must  be  exerted  on  the 
handles  of  the  press  in  order  to  rotate  the  rolls.  Greater 
pressure  or  the  use  of  more  blankets  will  give  a darker 
print  by  forcing  the  paper  farther  into  the  depressions  of 
the  copper.  It  will  probably  be  found  that  the  first  print 
is  unsatisfactory,  owing  to  the  plate  not  having  taken 
the  ink  perfectly,  and  a second  proof  should  always  be 
pulled  before  deciding  on  any  variations  of  treatment. 
If  the  plate  gives  too  dark  a print  an  improvement  may 
be  made  by  the  use  of  a thinner  ink  in  addition  to  the 
methods  given  in  the  previous  paragraph,  and,  as 
stated,  a stiffer  ink  will  give  darker  prints,  so  it  will  be 
apparent  that  great  variations  are  possible. 

Many  different  papers  may  be  used  for  printing 
and  the  worker  is  advised  to  obtain  a selection  and 
experiment  with  them.  Practically  all  papers,  however, 
must  be  used  in  a damp  state  and  this  may  be  attained 
by  soaking  them  in  water,  then  placing  two  or  three 
sheets  between  blotters  and  running  them  through  the 
press,  the  excess  of  water  being  thus  removed,  or,  if 
preferred,  each  sheet  may  be  dipped  quickly  into  water, 
the  sheets  being  stacked  and  placed  under  pressure  for 
several  hours. 

Modifications. — If  the  plate  is  to  be  strengthened 
as  a whole  a printer’s  roller  may  be  used  to  apply  what 
is  known  as  “finishing  ink.”  This  ink  may  either  be 
bought  or  be  made  up  as  follows,  this  formula  being 
taken  from  Herbert  Denison’s  “Treatise  on  Photo- 
gravure”: 

Asphaltum 1 34  ounces 

White  wax 3 ounces 

Stearine 3^4  ounces 

Spermaceti 7 ounces 


245 


TECHNIQUE  OF  PHOTOGRAVURE 


The  asphaltum  is  melted  in  a double  boiler  and  the 
other  ingredients  are  added  in  turn  with  constant 
stirring.  When  cool  it  will  be  stiff  and  may  be  thinned 
with  turpentine  for  use.  A small  quantity  is  placed 
on  a sheet  of  glass,  the  roller  is  passed  over  it  several 
times  in  different  directions  until  evenly  covered  with 
the  ink,  and  is  then  passed  over  a clean  sheet  of  glass 
until  only  a very  thin  film  of  ink  remains.  The  roller 
is  then  passed  lightly  back  and  forth  in  different 
directions  over  the  cleaned  copper  plate  until  the 
surface  is  lightly  charged  with  the  ink.  If  it  is  desired 
to  leave  the  high  lights  in  their  original  condition, 
strengthening  the  half-tones  and  the  shadows,  a little 
more  of  the  ink  may  be  taken  up  on  the  roller  and 
applied  to  the  plate,  when  the  shallowest  depressions 
will  be  filled  with  the  ink  and  will  not  be  affected  by 
the  application  of  the  etching  bath.  If  the  high  lights 
and  half-tones  are  to  be  left  unchanged  and  the  shadows 
strengthened,  a little  more  of  the  ink  may  be  applied, 
so  that  the  depressions  slightly  deeper  than  those  in 
the  lights  are  filled  with  the  ink.  After  inking,  the 
plate  is  thickly  dusted  with  asphaltum  powder  and  that 
which  does  not  adhere  to  the  ink  is  brushed  off  with  a 
soft  brush.  The  plate  is  then  heated  until  the  asphaltum 
becomes  incorporated  with  the  ink,  the  appearance  of 
the  plate  being  distinctly  changed  at  this  point.  When 
cool  the  back  and  edges  of  the  plate  are  protected  with 
asphaltum  varnish  and  the  plate  is  re-etched  for  the 
desired  length  of  time  in  a medium  strength  bath, 
afterward  being  cleaned  and  printed  as  before. 

It  is  also  possible  to  lay  a ground  on  the  cleaned 
copper  plate  in  the  dusting  box  and  set  it  by  heating, 

246 


MODIFICATIONS 


after  which  a weak  solution  of  perchloride  of  iron  may 
be  applied  to  such  portions  as  it  is  desired  to  strengthen, 
by  means  of  a soft  camel-hair  brush.  The  plate  should 
be  rinsed  from  time  to  time  and  dried  with  a clean 
cloth  or  there  is  danger  of  the  mordant  spreading  where 
it  is  not  desired.  It  is  also  possible  to  lighten  areas  by 
rubbing  down  the  hills  of  copper  with  a burnisher  or 
to  darken  portions  by  etching  with  a needle.  These 
methods,  however,  are  not  recbmmended,  since  the 
handwork  is  very  likely  to  be  apparent  and  it  is  decid- 
edly preferable  to  make  necessary  modifications  on 
the  original  negative  or  on  the  transparency,  even 
though  this  may  necessitate  etching  a new  plate. 

Evidently,  it  is  possible  to  make  multiple  prints 
in  photogravure,  by  inking  the  plate  and  running  the 
print  through  the  press  a second  time.  Some  method 
of  registration  must  be  used,  and  this  may  conve- 
niently take  the  form  of  pencil  marks  or  scratches  on  the 
zinc  or  paper  underlying  the  plate,  a line  being  run 
around  the  copper  plate  and  marks  being  made  at  the 
corners  of  the  printing  paper.  Of  course,  the  several 
printings  may  be  in  different  colors,  as  in  carbon  and 
gum,  and  it  possible  to  make  photogravures  in  full 
color  by  printing  from  a set  of  plates  made  from  a 
set  of  three-color  negatives,  though  this  requires  a 
high  degree  of  skill,  combined  with  very  careful 
manipulation. 


PART  IV 
COLOR 


CHAPTER  XVI 

DESIRABILITY  OF  COLOR  IN  PHOTOGRAPHY 

Almost  since  the  first  discovery  of  photography 
scientists  have  been  working  to  develop  some  method 
which  would  permit  of  reproducing  not  only  the  grada- 
tions of  natural  objects  but  also  the  colors,  and  within 
the  past  ten  years  considerable  success  has  crowned  their 
efforts,  in  that  methods  of  color  photography  have 
become  commercially  practical.  Before  that  time 
there  had  been  discovered  several  methods  which 
permit  of  accurate  reproduction  of  colors,  but  color 
photography  remained  a laboratory  experiment,  or  at 
least  required  laboratory  apparatus  and  very  careful 
work,  until  the  introduction  of  the  autochrome  plate 
by  Messrs.  Lumiere.  Since  that  time  several  plates 
more  or  less  resembling  the  autochrome  in  general 
character  have  been  placed  on  the  market,  and  Fred- 
erick Ives  has  standardized  an  older  process  in  such 
a manner  that  any  photographer  who  will  follow 
instructions  carefully  can  at  the  present  time  make 
satisfactory  photographs  in  full  color  of  practically 
any  natural  object. 

There  can  be  no  question  as  to  the  scientific  value 
of  these  processes,  since  they  render  possible  a perfect 
record  of  many  objects  of  the  highest  interest,  scientists 
hitherto  having  been  obliged  to  rely  on  the  compara- 
tively laborious  and  inaccurate  method  of  hand  color- 
ing, so  that  to  the  botanist,  the  zoologist,  the  patholo- 

251 


DESIRABILITY  OF  COLOR 


gist  and  to  many  other  workers  in  scientific  fields  color 
photography  renders  inestimable  assistance.  So  far  as 
the  artist  is  concerned,  however,  the  value  of  color 
photography  is  more  or  less  doubtful,  and  many  argu- 
ments are  advanced  against  its  use  in  this  field.  The 
writer  has  at  various  times  made  a great  many  color 
photographs  and,  like  nearly  every  photographer,  was 
very  enthusiastic  over  the  process  on  his  first  intro- 
duction to  it,  but  after  making  perhaps  two  hundred 
or  three  hundred  color  photographs  he  found  that, 
the  novelty  wearing  off,  the  results  failed  to  interest 
him.  In  the  search  for  a reason  for  this  condition  the 
writer  has  come  to  a very  definite  conclusion,  that  in 
the  present  state  of  the  art  the  use  of  color  is  not 
desirable. 

Some  time  ago,  in  conversation  with  two  well-known 
painters,  the  writer  said:  “How  much  do  you  feel 

that  photography  loses  by  being  unable  to  reproduce 
colors ?”  One  of  the  painters  answered,  “I  do  not 
feel  that  it  loses  anything.  If  you  examine  the  black- 
and-white  reproductions  of  the  works  of  the  great 
masters  you  will  find  that  in  many  cases  the  black- 
and-white  version  is  more  interesting  than  the  original, 
and  this  is  true  even  of  the  works  of  the  Venetians, 
such  as  Titian,”  and  turning  to  the  other  painter,  he 
asked:  “Isn’t  that  so?”  The  other  replied:  “Abso- 
lutely; and  if  Titian’s  color  couldn’t  make  a thing 
interesting,  nobody’s  could.”  Here,  then,  were  two 
painters,  both  of  them  able  men,  both  of  them  familiar 
with  the  best  works  in  their  medium,  and  both  of  them 
accustomed  to  work  in  color,  who  felt  that  a black-and- 
white  art  could,  other  things  being  equal,  be  quite  as 

252 


POWER  OF  COLOR 


interesting  and  as  valuable  as  a color  art.  The  average 
layman  is  actually  thrilled  by  the  sight  of  a photo- 
graph in  color,  as  witness  the  immense  sale  in  this 
country  of  hand-colored  prints,  so  it  must  be  apparent 
that  the  layman  and  the  artist  are  pleased  by  entirely 
different  aspects  of  art. 

To  determine  the  cause  of  the  different  feeling 
which  exists  between  laymen  and  artists,  it  may  be 
well  to  consider  first  the  appeal  made  by  different  forms 
of  art,  and  it  will  be  found  that  every  art  possesses  in 
varying  proportions  an  admixture  of  both  sensuous  and 
intellectual  appeal.  Thus,  the  appeal  of  music  is 
almost  entirely  to  the  senses,  the  intellectual  part 
being  so  slight  as  to  be  not  worth  considering;  that  of 
prose  writing  is  almost  entirely  intellectual;  that  of 
poetry  may  be  composed  of  intellectual  and  sensuous 
constituents  in  almost  any  proportion;  that  of  archi- 
tecture is  almost  exclusively  intellectual,  and  so  on. 
It  is  of  course  apparent  that,  whereas  an  intellectual 
appeal  is  to  the  logical  faculties,  a sensuous  one  is  to 
the  physical  portion  of  the  individual;  that  is,  certain 
nerves  respond  to  certain  stimuli,  thus  affecting  in 
greater  or  less  degree  the  entire  nervous  system.  It 
is  well  known  that  certain  classes  of  music  may  stimu- 
late the  hearers  to  almost  entire  self-forgetfulness, 
inducing  either  tears  or  great  exaltation,  but  it  is  not 
so  well  known  that  color  possesses  in  lesser  degree  the 
same  power.  It  has  been  found  that  the  warmer  colors, 
such  as  red,  orange  and  yellow,  stimulate  the  nervous 
system  very  markedly  through  the  action  on  the  optic 
nerve,  so  that  no  neurologist  would  permit  a patient 
to  remain  in  a room  finished  in  red,  whereas  the  cooler 

253 


DESIRABILITY  OF  COLOR 


colors  are  distinctly  quieting  to  the  nervous  system. 
Hence  it  follows  that  the  combination  of  different 
colors  in  their  suitable  proportions  may  produce  a 
sensuous  excitement  or  a sensuous  calm  resembling 
that  aroused  by  music.  It  seems  clear,  then,  that  the 
function  of  color  in  art  is  to  heighten  the  effect  by 
producing  in  the  spectator  a nervous  condition  which 
renders  him  more  receptive  to  the  idea  which  the 
artist  wishes  to  convey,  and  that  when  the  artist 
wishes  to  appeal  solely  or  principally  to  the  intellectual 
faculties,  he  will  refrain  in  great  measure  from  the  use 
of  color,  and  will  certainly  employ  only  subdued  colors. 
Examination  of  the  works  of  those  artists  who  are 
noted  for  their  psychic  insight,  such  as  Rembrandt  and 
Velazquez,  shows  that  these  men  employed  color  to  a 
very  limited  extent,  their  work  being  conspicuous  for 
the  use  of  secondary  and  tertiary  colors,  almost  to  the 
exclusion  of  primaries. 

Since  photography  is  capable  of  reproducing  more 
perfectly  than  any  other  art  the  outlines  and  grada- 
tions of  natural  objects,  and  since  it  reproduces  colors 
with  comparative  difficulty,  it  would  seem  that  the 
worker  with  the  camera  is  particularly  favored  if  he 
desires  to  produce  a result  which  shall  appeal  to  the 
logical  faculties  rather  than  to  the  senses,  and  this 
serves  to  indicate  the  difference  of  opinion  existing 
between  artists  and  laymen  as  to  the  value  of  color 
in  photography,  for  the  artist  is  necessarily  trained 
to  observe  and  to  think,  whereas  the  average  individual 
does  neither.  Many  persons  will  be  inclined  to  question 
this  statement  as  to  the  failure  of  the  average  person 
to  observe  his  surroundings  and  to  employ  his  logical 

254 


LIMITATIONS 


faculties,  but  investigation  shows  that  it  is  quite 
justified. 

The  photographer  who  wishes  to  work  in  color  is, 
generally  speaking,  limited  as  to  the  ability  to  produce 
various  effects,  since  he  cannot  modify  the  internal 
relationship  of  his  colors  with  the  same  ease  that  the 
painter  can  and  it  therefore  seems  a mistake  for  a 
worker  whose  desire  is  to  effect  a sensuous  stimulus 
to  employ  the  camera,  but  the  possibilities  of  appealing 
to  the  logical  faculties  by  means  of  photography  seem 
almost  unlimited  and  the  writer,  therefore,  feels  that 
color  photography  does  not  merit  serious  consideration 
by  the  pictorial  worker,  j 


CHAPTER  XVII 

THE  TECHNIQUE  OF  COLOR  PHOTOGRAPHY 

All  of  the  processes  of  color  photography  depend 
fundamentally  on  the  fact  that  any  color  may  be 
produced  by  the  blending  of  two  or  three  of  the 
primary  colors,  the  variations  of  method  lying  in  the 
means  employed  for  securing  the  desired  result.  In 
the  autochrome,  Paget,  and  kindred  processes,  the 
result  is  produced  by  interposing  a screen  of  fine  grains 
of  the  primary  colors  between  a transparency  and  the 
illuminant,  the  photograph  being  examined  by  trans- 
mitted light.  In  the  Sanger-Shepherd,  Hess-Ives, 
three-color  carbon,  and  three-color  gum  processes, 
prints  are  made  in  suitable  dyes  or  pigments  from  a 
set  of  three  negatives,  each  of  which  has  recorded  only 
one  of  the  primary  colors,  the  superposition  of  these 
three  prints  giving  a reproduction  of  the  original 
subject. 

The  Autochrome  Process. — This  is  perhaps  the 
simplest  of  the  color  processes  and  is  the  easiest  to 
manipulate.  The  plates,  which  are  obtainable  com- 
mercially, are  made  in  the  following  manner:  Starch 
grains  approximating  1/1500  inch  in  diameter  are  dyed 
in  the  three  primary  colors,  being  afterward  mixed  in 
suitable  proportion  and  attached  firmly  to  a glass  plate. 
Pressure  is  then  applied  so  that  the  starch  grains  are 
flattened  out  and  any  interstices  are  filled  by  the 
spreading  of  the  grains.  A panchromatic  emulsion  is 
then  placed  over  this  color  screen  and  the  plate  is  ready 

256 


THE  AUTOCHROME  PROCESS 


for  exposure.  It  should  be  taken  from  the  package  in 
absolute  darkness  and  placed  in  the  camera  with  the 
glass  side  toward  the  lens,  so  that  the  light  must  pass 
through  the  color  screen  before  reaching  the  sensitive 
emulsion.  Black  cards  are  furnished  with  the  plates 
and  one  of  these  should  be  placed  in  contact  with  the 
emulsion  before  loading  the  plate-holder,  since  the 
emulsion  is  much  thinner  and  more  delicate  than  that 
on  an  ordinary  plate  and  scratches  or  pin-holes  cannot 
be  spotted  out  with  the  facility  that  is  possible  in  ordi- 
nary photography.  A special  ray -filter  must  be  placed 
on  the  lens  and  allowance  of  course  must  be  made  in 
focussing  for  the  fact  that  the  emulsion  is  farther  from 
the  lens  than  is  ordinarily  the  case.  The  exposure  is 
much  longer  than  with  ordinary  plates,  approximately 
sixty  times  as  much  exposure  being  required  as  with  a 
Kodak  film.  The  latitude  of  the  emulsion  is  much  less 
than  that  of  an  ordinary  plate  and  exposure  must  be 
very  nearly  correct  or  the  color  rendering  will  be  decid- 
edly faulty,  10  per  cent,  in  either  direction  being  enough 
to  introduce  serious  defects  in  the  finished  result. 

If  we  consider  one  particular  color  it  will  be  easier 
to  follow  the  theory  of  the  subsequent  processes,  so  we 
will  fix  our  attention,  say,  on  an  area  of  red  in  the  sub- 
ject, which  occupies  perhaps  half  a square  inch  on  the 
plate.  Each  of  the  colored  starch  grains  acts  as  a 
filter,  the  violet  and  green  absorbing  the  red  rays 
completely  before  they  reach  the  sensitive  emulsion, 
the  red  grains,  on  the  other  hand,  permitting  the  red 
rays  to  pass  freely.  Hence  it  follows  that  the  red  light 
reflected  from  the  subject  affects  the  sensitive  emulsion 
only  directly  over  the  red  grains  and  on  development 

17  257 


COLOR  PHOTOGRAPHY 


we  have  a deposit  of  metallic  silver  over  the  red  grains, 
while  the  silver  bromide  remains  unaffected  over  the 
violet  and  green  grains.  When  development  is  com- 
plete, the  plate  is  immersed  in  a solution  which  dis- 
solves metallic  silver  but  does  not  attack  the  unreduced 
haloid  salt.  The  plate  is  then  exposed  to  light  and  is 
again  developed,  with  the  result  that  there  is  a space 
of  transparent  gelatine  over  each  red  grain  in  the  area 
under  consideration  and  an  opaque  deposit  of  metallic 
silver  over  each  violet  and  green  grain,  so  that  on  hold- 
ing the  plate  up  to  the  light  the  area  in  question  will 
appear  red  by  reason  of  the  fact  that  the  red  starch 
grains  absorb  the  violet  and  green  components  of 
white  light,  permitting  only  the  red  rays  to  pass 
through.  A like  result  occurs  in  the  case  of  violet  and 
green  objects,  and  since  we  have  found  that  secondary 
and  tertiary  colors,  such  as  blue,  yellow,  brown,  etc., 
are  made  up  by  a suitable  mixture  of  two  or  more 
primaries,  it  follows  that  the  colored  starch  grains  sift 
the  primaries  reflected  from  natural  objects  and  the 
appearance  of  the  subject  is  thus  reproduced  not  only 
in  gradation  but  also  in  color. 

It  is  possible  to  correct  to  a certain  extent  errors 
of  exposure  by  variations  in  development,  for  if  the 
plate  be  developed  entirely  by  time  the  effect  of  over- 
exposure is  to  give  blank  high  lights,  whereas  under- 
exposure results  in  general  heaviness.  There  are  many 
methods  given  for  effecting  this  correction,  most  of 
them  being  based  on  the  time  required  for  the  image  to 
appear  in  the  developer.  Since  the  emulsion  is  pan- 
chromatic, the  light  permissible  in  the  dark  room  is  of 
a very  dim  green  nature  and  it  is  difficult  to  follow 

258 


THE  AUTOCHROME  PROCESS 


the  process  of  development  by  inspection,  so  for  this 
reason  the  writer  prefers  to  desensitize  the  plate  by 
immersing  it  for  five  minutes  in  total  darkness  in  a 


bath  of 

Water 10  ounces 

Potassium  metabisulphite ^ ounce 


after  which  it  is  rinsed  for  about  thirty  seconds  under 
the  faucet  and  development  is  carried  out  by  an  ordi- 
nary red  light.  Any  standard  developer  may  be  used, 
although  pyro  is  not  advised,  as  this  gives  a general 
warm  tone.  For  the  sake  of  convenience  the  writer 
prefers  to  use  rodinal  or  the  metol-hydroquinone 
formula  given  in  Chapter  IV,  using  about  one  ounce 
of  the  stock  solution  to  fifteen  ounces  of  water.  It  is 
impossible  to  state  definitely  just  how  far  development 
should  be  carried,  as  experience  is  the  only  certain 
guide,  but  generally  speaking  it  should  be  continued 
until  the  high-lights  have  apparently  begun  to  grow 
thinner;  that  is,  the  lights  will  gain  in  density  at  first 
and  after  a time  will  assume  a slightly  grayish  appear- 
ance, this  being  the  point  at  which  development  should 
be  stopped.  The  plate  is  then  rinsed  under  the  faucet 
for  about  thirty  seconds. 

The  next  step  is  reversal,  and  numerous  formulae 
are  given  for  this  purpose,  the  function  of  the  reversing 
solution  being  to  dissolve  out  the  metallic  silver  result- 
ing from  development.  The  formula  which  the  writer 
prefers  is  as  follows: 


Water 7 ounces 

Potassium  bichromate 25  grains 

Sulphuric  acid,  dilute 7 drams 


This  is  less  likely  to  cause  black  specks  than  the 
usual  potassium  permanganate  formula.  The  plate  is 

259 


COLOR  PHOTOGRAPHY 


allowed  to  remain  in  this  solution  for  about  five  minutes 
in  all,  and  after  a minute  or  so  in  this  bath  should  be 
carried  out  into  daylight,  the  light  of  an  ordinary  room 
being  sufficient.  If  development  takes  place  at  night 
the  plate  may  be  exposed  for  five  minutes  a few  inches 
from  a strong  light,  such  as  a Welsbach  or  incandescent 
electric  lamp.  If  preferred,  the  plate  may  be  rinsed 
after  five  minutes  in  the  reversing  solution  and  set  up 
to  dry,  the  subsequent  operations  being  carried  out  at 
any  later  time,  and  this  technique  possesses  the  ad- 
vantage of  diminishing  the  likelihood  of  frilling. 

After  reversing,  the  plate  is  rinsed  for  about  thirty 
seconds  under  the  faucet  and  is  then  redeveloped  for 
about  five  minutes  in  the  original  developer,  after 
which  it  is  rinsed  for  thirty  seconds  under  the  faucet 
and  set  up  to  dry. 

When  dry  the  emulsion  should  be  flowed  with  the 
special  varnish  provided  by  the  manufacturers  of  the 
plate,  since  this  tends  to  preserve  the  purity  of  the 
colors  and  to  protect  the  film  from  injury.  After 
varnishing,  the  plate  should  be  bound  up  with  a cover 
glass  after  the  fashion  of  a lantern-slide,  and  may  then 
be  depended  on  to  remain  in  satisfactory  condition  for 
an  indefinite  length  of  time,  though  if  it  is  exposed  to 
direct  sunlight  or  to  great  heat  for  prolonged  periods 
the  colors  may  fade  or  the  film  may  crack. 

The  chief  causes  of  failure  in  autochrome  work  are 
over-  and  under-exposure  and  frilling.  This  last  will 
probably  not  be  serious  if  all  the  solutions  are  kept  at  a 
temperature  between  60°  and  65°  Fahrenheit  and  the 
plate  is  not  handled  with  the  fingers.  It  is  therefore 
advised  to  be  careful  regarding  temperature  and  to 

260 


THE  PAGET  PROCESS 


allow  the  plate  to  remain  in  one  tray  as  much  as  pos- 
sible during  all  the  processes,  but  if  the  temperature 
cannot  be  kept  at  the  proper  point  immersion  of  the 
plate  for  two  or  three  minutes  in  a 5 per  cent,  formal- 
dehyde bath,  followed  by  rinsing,  will  help  matters. 
The  formaldehyde  should  be  used  before  desensitizing. 

If  a developer  which  works  without  alkali  is  em- 
ployed the  likelihood  of  frilling  is  still  further  reduced, 
and  many  photographers  prefer  amidol  and  dianol  for 
this  reason.  Scratches  on  the  film  may  cause  green 
spots  through  permitting  the  developer  to  penetrate  to 
the  color  screen  and  causing  the  dye  in  the  starch  grains 
to  run.  Black  specks  may  sometimes  be  removed  by 
the  use  of  the  reversing  solution  applied  with  a fine 
pointed  brush,  but  retouching  is  in  general  exceedingly 
difficult  and  uncertain.  Any  of  the  methods  of  intensi- 
fication or  reduction  given  in  Chapter  VI  may  be  used 
with  autochrome  plates,  but  it  should  be  borne  in 
mind  that  the  film  is  exceedingly  thin  and  any  solution 
which  is  employed  should  be  diluted  to  approximately 
one-tenth  the  concentration  at  which  it  is  used  for 
general  work,  or  the  action  will  be  so  rapid  as  to  make 
control  difficult. 

The  Paget  Process. — Fundamentally,  the  Paget 
process  is  identical  with  the  autochrome  but  differs 
from  it  in  that  the  color  screen  and  the  sensitized 
emulsion  are  on  different  pieces  of  glass.  The  sensi- 
tized plate  is  first  placed  in  the  holder  and  the  color 
screen  is  laid  over  it,  the  exposure  being  made  as  with 
the  autochrome  plates.  Development  may  be  either 
by  time  or  by  inspection,  and  the  plate  is  washed 
and  dried  in  the  usual  manner,  the  color  screen  being 

261 


COLOR  PHOTOGRAPHY 


preserved  for  subsequent  use.  From  this  negative  a 
transparency  is  made  on  a dry  plate  by  contact  printing 
and  it  is  possible  to  compensate  to  a considerable  extent 
for  errors  in  exposure  and  development  during  the 
process  of  making  the  transparency.  This  transparency 
is  then  registered  with  a special  viewing  screen  similar 
to  the  taking  screen,  though  differing  from  it  somewhat 
in  the  adjustment  of  the  colors,  and  the  two  are  bound 
together  with  passepartout  tape  or  lantern  slide  binding. 
It  will  be  seen  that  the  Paget  process  is  capable  of 
giving  any  number  of  duplicates,  since  the  color  screens 
are  regular  and  any  number  of  identical  viewing  screens 
may  be  bound  up  with  transparencies. 

The  autochrome  and  Paget  processes  differ  not  only 
in  the  possibility  of  duplication  which  exists  in  the 
latter,  but  also  in  the  fact  that  the  color  screen  in  the 
Paget  plates  is  far  more  transparent  than  in  the  auto- 
chromes, since  it  consists  simply  of  aniline  dyes  laid  on 
the  transparent  substratum,  no  starch  grains  being 
used.  The  results  are  therefore  far  more  luminous  than 
any  autochrome  can  ever  be. 

A disadvantage  of  the  Paget  process  lies  in  the  fact 
that  the  glass  plates  must  be  carefully  selected  for  flat- 
ness, since  unless  the  films  of  both  negative  and  positive 
plates  are  in  optical  contact  with  the  color  screens  it 
will  be  impossible  to  secure  satisfactory  results.  One 
worker  advises  cementing  the  transparency  and  the 
viewing  screen  together  with  Canada  balsam  thinned 
with  xylol,  a small  pool  of  the  cement  being  poured  on 
the  screen  and  the  transparency  pressed  on  it  so  as  to 
force  the  balsam  over  the  whole  surface.  The  two  are 
then  held  up  to  the  light  and  the  transparency  is  moved 

262 


THE  CONNECTICUT  RIVER 
BY  W.  E.  MACNAUGHTON 

From  a Platinum  Print 


THE  HESS-IVES  PROCESS 


about  until  register  is  secured,  the  plates  being  then 
clipped  firmly  together  and  placed  in  a warm  oven  until 
the  balsam  is  hard,  when  the  whole  is  bound  up  with 
tape.  This  plan  is  said  to  insure  the  avoidance  of  paral- 
lax and  make  possible  the  use  of  transparency  plates 
which  are  not  optically  flat. 

The  Hess-Ives  Process. — As  has  been  said,  the 
Hess-Ives  process  is  fundamentally  identical  with  a 
well-known  and  comparatively  old  method  of  color 
photography,  the  improvements  consisting  of  a means 
whereby  all  three  of  a set  of  three-color  negatives  may 
be  made  with  one  exposure  in  an  ordinary  camera,  and 
the  standardization  of  the  subsequent  operations  so 
that  they  may  be  carried  out  with  precision  by  any 
reasonably  careful  worker. 

In  its  original  form  this  process  required  a special 
camera,  but  a later  improvement  has  done  away  with 
this,  and  any  camera  may  be  employed,  the  only  special 
apparatus  necessary  being  a plateholder.  In  this 
holder  is  placed  a pack  consisting  of  a red-sensitive 
plate,  a green-sensitive  film,  and  a blue-sensitive  plate, 
firmly  bound  together,  the  film  being  between  the  two 
plates.  The  blue-sensitive  plate  is  toward  the  lens,  and 
when  exposure  is  made  this  plate  records  the  violet  ele- 
ment of  the  light  forming  the  image,  permitting  the 
green  and  red  rays  to  pass  through  the  emulsion.  The 
green  rays  affect  the  sensitive  emulsion  on  the  film, 
which  in  turn  allows  the  red  rays  to  pass  through  and 
reach  the  red-sensitive  plate.  The  exposure  required 
is  somewhat  less  than  for  the  autochrome  plate,  which 
is  rated  at  F/14  on  the  Wynne  meter,  the  speed  of  the 
Hess-Ives  pack  being  about  F/20. 


263 


COLOR  PHOTOGRAPHY 


The  three  plates  are  developed  for  a standard  time 
in  a standard  developer  at  standard  temperature,  the 
time  of  development  being  variable  for  special  effects 
if  so  desired,  or  factorial  development  may  be  used. 

The  three  negatives  are  printed  similarly  on  a 
bichromated  gelatine  film  which  is  supported  on  trans- 
parent celluloid,  and  the  printed  film  is  developed  in 
hot  water,  with  the  result  that  certain  portions  of  the 
gelatine  are  dissolved  off  from  the  support  exactly  as 
is  the  case  in  carbon  printing.  The  films  are  then  dyed 
in  suitable  dyes,  each  film  of  course  taking  up  an  amount 
of  the  dye  proportionate  to  the  amount  of  gelatine  re- 
maining on  the  support,  and  the  three  dyed  films  are 
then  bound  up  in  register,  a transparency  in  natural 
colors  resulting. 

If  a print  on  paper  is  desired  one  print  is  made  on 
paper,  the  other  two  being  on  celluloid  and  the  three 
being  cemented  firmly  together.  It  will  be  seen  from 
this  that  the  Hess-Ives  process  presents  one  conspicu- 
ous advantage  over  the  autochrome  and  Paget  pro- 
cesses, in  that  it  gives  prints  which  may  be  examined 
by  reflected  light,  the  other  processes  requiring  trans- 
mitted light  for  examination  of  the  result.  Also  it  has 
the  advantage  over  the  autochrome  process  that  any 
desired  number  of  prints  or  transparencies  may  be 
made  from  a set  of  negatives,  and  a further  advantage 
is  that  relative  modifications  of  color  may  easily  be 
made  by  dyeing  one  film  more  strongly  than  the  others, 
or  by  brush-work  in  any  particular  area  of  any  of  the 
films,  this  last-named  quality  being  of  great  value  to 
the  pictorial  worker. 

To  give  full  details  of  the  Hess-Ives  process  would 

264 


THREE-COLOR  GUM 


occupy  more  space  than  can  be  afforded  in  a book  of 
this  nature  and  would  furthermore  be  superfluous, 
since  these  can  readily  be  obtained  from  the  manu- 
facturers. It  may,  however,  be  said  that  this  process  is 
strongly  to  be  recommended  to  the  pictorial  worker 
who  desires  to  employ  color,  and  for  this  purpose  is  the 
most  desirable  of  all,  with  the  possible  exception  of 
three-color  gum,  the  chief  drawback  of  the  Hess-Ives 
method  lying  in  the  fact  that  the  surface-texture  of 
the  print  is  always  approximately  that  of  a collodion 
print,  it  being  impossible  to  use  a rough-surface  paper 
as  a support. 

Three-Color  Gum. — If  a set  of  three-color  nega- 
tives is  made,  using  a suitable  ray -filter  so  that  one  of 
the  plates  records  only  the  red  element  of  the  light 
reflected  from  the  subject,  another  only  the  green  ele- 
ment and  the  third  only  the  violet  element,  it  is  possible 
to  print  from  these  plates  in  suitable  pigments,  super- 
imposing the  second  and  third  printings  on  the  first,  with 
the  result  that  a completed  piint  shows  an  approxi- 
mately correct  reproduction  of  the  object  photo- 
graphed. The  printing  may  be  either  in  gum  or  in 
carbon,  but  the  former  is  to  be  preferred  for  several 
reasons.  First,  it  permits  of  a more  accurate  balance 
among  the  pigments,  the  filters  and  the  plates,  such 
a balance  being  necessary  for  correct  rendering  of 
color.  Second,  it  permits  the  use  of  a paper  base  of 
practically  any  desired  texture,  whereas  if  carbon  tissue 
is  used  the  support  must  be  smooth,  since  the  print 
must  be  made  by  double  transfer,  single  transfer  not 
allowing  the  worker  to  determine  whether  or  not  the 
three  tissues  have  been  properly  exposed  and  developed 

265 


COLOR  PHOTOGRAPHY 


until  the  print  is  complete,  when  it  is  too  late  to  make 
any  changes.  Third,  it  is  easier  to  introduce  local 
modifications  of  color  in  gum  than  in  carbon,  this  being 
sometimes  desirable  for  pictorial  effect. 

There  are  two  methods  of  making  the  set  of  three- 
color  negatives,  the  first  involving  the  use  of  three 
panchromatic  plates,  one  for  each  color  sensation  rec- 
ord the  second  using  different  types  of  plates  for  the 
different  records;  that  is,  a panchromatic  for  the  red 
sensation,  an  orthochromatic  for  the  green  sensation, 
and  an  ordinary  for  the  violet  sensation.  The  first 
method  has  the  advantage  that  it  is  easier  to  obtain 
identical  gradation  in  all  three  negatives,  since  the 
quality  of  all  the  plates  in  one  batch  is  identical,  whereas 
the  quality  of  different  emulsions  varies  widely.  The 
second  method  has  the  advantage  that  it  is  not  neces- 
sary to  adjust  the  absorption  of  the  filters  with  such 
great  precision  as  in  the  first  case,  for  it  is  apparent 
that  if  the  violet  screen  transmits  some  red  light,  this 
will  affect  a panchromatic  plate  but  will  not  affect  an 
ordinary  one,  and  the  like  is  true  of  the  green  sensa- 
tion filter.  However,  if  the  filters  are  carefully  made  by 
experienced  manufacturers  they  may  be  counted  on  to 
do  the  work  satisfactorily,  and  the  writer  prefers  to 
use  panchromatic  plates  for  all  three  negatives  on 
account  of  the  greater  facility  in  handling. 

In  making  the  exposure  some  arrangement  must  be 
used  whereby  the  three  filters  can  readily  be  substi- 
tuted for  one  another  in  front  of  or  behind  the  lens, 
and  such  fittings  are  obtainable  commercially.  It  is 
convenient,  though  not  necessary,  to  have  a sliding 
back,  so  that  the  plates  may  be  shifted  along  to  be 

266 


THREE-COLOR  GUM 


exposed  one  after  the  other  without  the  necessity  for 
changing  plate  holders,  but  even  without  such  a fitting 
the  writer  has  made  indoor  portraits,  the  total  time 
required  for  changing  the  plate-holders  and  filters  and 
for  the  exposures  being  about  two  minutes,  a time  which 
compares  very  favorably  with  the  exposure  required  in 
similar  conditions  on  an  autochrome  plate. 

It  is  necessary  to  use  a corrected  lens,  preferably 
an  anastigmat,  since  if  the  lens  has  any  chromatic  aberra- 
tion the  three  images  will  not  all  be  in  focus  and  will 
not  all  be  of  the  same  size,  thus  rendering  even  reason- 
ably good  definition  impossible.  The  lens  should  pref- 
erably be  as  fast  as  possible  in  order  to  reduce  the  time 
required  for  exposure. 

For  accurate  work,  such  as  reproduction,  the  filters 
should  be  of  the  class  known  as  “optical  flats”  since 
a slight  variation  in  the  parallelism  of  the  two  sides  of 
the  filter  is  sufficient  to  introduce  variations  in  the  sizes 
of  the  three  images.  For  pictorial  work,  however,  such 
expensive  filters  as  these  are  not  required,  and  the 
writer  has  done  perfectly  satisfactory  work  using  filters 
which  consisted  of  dyed  gelatine  films,  not  even  ce- 
mented but  merely  bound  between  lantern-slide  cover- 
glasses.  Still,  such  extremely  inaccurate  methods  are 
by  no  means  advised  and  the  filters  should  be  at  least 
reasonably  good  ones.  It  will  be  found  that  very  dif- 
ferent times  of  exposure  are  required  with  the  different 
filters  and  the  relative  increase  dependent  on  each  filter 
should  be  obtained  from  the  manufacturer,  since  the 
multiplying  factor  varies  with  different  batches  of 
emulsion.  At  least  one  manufacturer  in  this  country 
supplies  this  information  with  each  box  of  plates. 

267 


COLOR  PHOTOGRAPHY 


Development  should  be  by  time,  and  if  panchromatic 
plates  are  used  for  all  the  negatives,  they  should  be 
developed  simultaneously  in  a tank,  since  identity  of 
gradation  is  thus  insured. 

Whatever  method  of  development  is  employed  the 
negatives  should  be  much  softer  than  for  ordinary 
black-and-white  work  and  should  be  somewhat  softer 
even  than  the  negatives  for  ordinary  gum  printing.  It 
is  well  to  make  on  the  corner  of  each  plate  some  mark 
of  identification  before  the  plate  is  developed,  since  the 
three  negatives  will  be  closely  similar  and  it  will  not 
be  easy  to  distinguish  one  from  another. 

The  worker  who  wishes  to  print  in  three-color  gum 
will  probably  do  well  to  employ  the  Hess-Ives  process 
for  making  the  negatives,  since  it  is  much  easier  to 
produce  a set  of  three-color  negatives  by  this  method 
than  by  making  separate  exposures  with  filters. 

It  is  necessary  to  print  each  plate  in  a color  com- 
plementary to  that  of  the  taking  filter,  as  may  readily 
be  understood  when  we  consider  that  the  filter  trans- 
mits light  of  its  own  color  and  that  the  blank  spaces  in 
the  negative  represent  the  absence  of  this  particular 
color;  that  is,  in  the  violet  sensation  negative  the  de- 
posit of  silver  is  caused  by  violet  light  and  where  there 
is  no  deposit  of  silver  its  absence  is  due  to  the  fact  that 
the  filter  absorbed  the  green  and  red  components  of 
the  light  reflected  from  the  subject.  Therefore  the 
violet  sensation  negative  must  be  printed  in  yellow 
(green  + red)  and  similarly  the  green  sensation  negative 
must  be  printed  in  magenta  (violet  + red)  and  the  red 
sensation  negative  in  blue  (violet  + green).  It  is  not 
possible  to  give  a definite  formula  for  the  coating  mix- 

268 


THREE-COLOR  GUM 

tures,  since  this  will  depend  on  the  subject,  on  the 
method  of  making  the  negatives,  and  on  the  filters 
used,  but  the  manufacturers  of  supplies  for  the  three- 
color  process  furnish  ink  testers  or  color  charts  which 
show  the  color  to  be  used  for  each  printing,  and  the 
worker  can  match  these  colors  by  combining  different 
pigments.  The  pigments  should,  of  course,  be  trans- 
parent ones  rather  than  opaque,  and  it  is  usual  to  make 
the  blue  printing  first,  since  this  color  is,  generally 
speaking,  less  transparent  than  yellow  and  magenta. 
In  some  cases  it  will  be  found  that  a blue-print  will 
serve  for  the  printing  of  the  red  sensation  negative  and 
this  simplifies  matters  somewhat,  since  a blue-print  is 
easier  to  make  than  a gum  print. 

In  order  to  obtain  the  proper  gradations  and  depth 
it  may  be  necessary  to  print  twice  or  more  in  each 
color,  and  it  will  often  be  found  that  a light  printing 
of  black  from  a fourth  negative  made  with  a corrective 
filter  will  be  helpful,  since,  although  the  three  printings 
of  blue,  yellow,  and  magenta  should  theoretically  give 
a black  where  such  existed  in  the  original  subject,  prac- 
tically they  will  not  do  so,  owing  to  the  impossibility 
of  obtaining  theoretically  perfect  pigments. 

Enlarged  negatives  may,  of  course,  be  made  when 
large  prints  are  desired,  and  although  errors  in  these 
may  be  corrected  to  a great  extent  in  printing,  it  will 
nevertheless  be  found  advantageous  to  make  the  three 
large  negatives  as  uniform  with  the  originals  as  pos- 
sible, since  much  trouble  is  thus  avoided. 

The  three-color  gum  process  is  an  exceedingly  labori- 
ous one  and  in  the  writer’s  opinion  the  result  does  not 
repay  the  effort  expended,  though  the  worker  who  de- 

269 


COLOR  PHOTOGRAPHY 


sires  color  prints  and  is  willing  to  give  the  time  neces- 
sary to  their  production  will  probably  find  this  process 
more  satisfactory  from  an  artistic  standpoint  than  any 
other. 

Since  writing  the  above  remarks,  the  writer  has 
learned  that  the  Hess-Ives  Corporation  is  working  on 
a standardized  method  for  three-color  gum  printing, 
which  should  prove  very  valuable  to  the  pictorial  worker 
in  color. 

Multi-Color  Gum  Printing. — Some  workers  en- 
deavor to  produce  striking  effects  by  printing  in  arbi- 
trarily chosen  colors  from  a single  negative,  shading 
portions  of  the  negative  while  printing  one  color  and 
the  remainder  of  the  negative  while  printing  the  other 
colors,  or  removing  the  first  color  from  certain  areas  of 
the  print  by  scrubbing  with  a stiff  brush  and  allowing 
these  portions  to  print  in  the  second  or  third  color, 
these  in  turn  being  removed  from  areas  where  they  are 
not  desired.  The  writer  has  never  seen  a print  of  this 
sort  which  possessed  any  artistic  merit  whatever  or 
could  be  considered  anything  except  thoroughly  un- 
satisfactory. 


PART  V 

MISCELLANEOUS 


CHAPTER  XVIII 


PHOTOGRAPHY  BY  ARTIFICIAL  LIGHT 

In  many  cases  it  will  be  found  necessary  or  desirable 
to  make  photographs  at  a time  when  daylight  is  not 
available  for  exposure,  and  when  this  occurs  recourse 
may  be  had  to  one  of  several  forms  of  artificial  illumina- 
tion, each  of  these  having  some  special  merit  of  its  own. 

The  Mercury-Vapor  Arc. — This  consists  of  one 
or  more  glass  tubes  of  a length  determined  by  the  class 
of  work  for  which  it  is  intended,  these  being  filled  with 
mercury  vapor  at  comparatively  low  pressure.  A cur- 
rent of  electricity  is  passed  through  the  tube  or  tubes 
and  these  glow  with  a high  luminosity  somewhat  re- 
sembling that  of  the  familiar  Crookes  tube  which  in 
modified  form  is  used  for  X-ray  work.  Exposures  of 
fairly  brief  duration  may  be  made  in  certain  circum- 
stances by  this  illuminant,  it  being  greatly  in  vogue 
for  portraiture,  and  when  used  for  this  purpose  per- 
mitting exposures  of  about  five  seconds  with  a lens 
working  at  F/8  and  a moderately  fast  plate.  The  use- 
fulness of  this  form  of  lamp,  however,  is  restricted  by 
the  well-known  law  which  says  that  the  amount  of  light 
falling  on  the  subject  varies  inversely  as  the  square  of 
the  distance  from  the  source  of  illumination,  though 
for  home  portraiture  it  is  in  some  cases  to  be  recom- 
mended, since  it  is  made  in  a convenient  portable  form 
and  can  be  attached  to  any  lamp  socket,  the  current 
consumption  being  small. 

18 


273 


BY  ARTIFICIAL  LIGHT 


The  character  of  the  light  given  by  the  mercury- 
vapor  arc  is,  however,  very  different  from  that  of  day- 
light, since  the  lamp  in  question  emits  practically  none 
but  ultra-violet  and  violet  rays,  being  devoid  of  red  and 
green  waves.  Therefore  correct  color  rendering  must 
not  be  expected  if  the  subject  contains  any  red  or  green, 
even  though  a panchromatic  plate  is  used.  For  this 
reason  the  writer  prefers  not  to  employ  the  mercury- 
vapor  arc  for  portraiture,  although  it  is  exceedingly 
valuable  for  enlarging,  lantern-slide  work,  and  contact 
printing,  the  writer  having  made  platinum  prints  from 
an  average  negative  with  five  minutes’  exposure  a foot 
or  more  from  a two-tube  lamp  of  this  character,  so  it 
follows  that  to  a person  whose  photographic  work  must 
be  done  largely  at  night,  the  mercury-vapor  arc  will 
be  of  great  assistance. 

Incandescent  Gas. — The  Welsbach  light  furnishes 
a very  desirable  type  of  illuminant  for  portrait  work, 
since  it  approximates  more  closely  the  composition  of 
daylight  than  is  the  case  with  any  other  of  the  familiar 
lights.  Since,  however,  this  light  is  relatively  richer  in 
red  rays  than  daylight,  comparatively  brief  exposures 
are  possible  if  panchromatic  plates  are  used,  a single 
Welsbach  mantle  six  feet  from  the  sitter  giving  suffi- 
cient illumination  to  permit  of  full  exposure  in  ten  sec- 
onds with  a fast  panchromatic  plate  and  a lens  work- 
ing at  F/8,  whereas  if  an  orthochromatic  plate  is  used 
two  minutes  may  be  required.  Increasing  the  number 
of  mantles  of  course  decreases  the  time  necessary ,.  and 
some  photographers  prefer  to  employ  for  night-work 
a frame  carrying  half  a dozen  or  more  Welsbachs, 
these  being  connected  with  a gas  outlet  by  means 

274 


FLASH-LIGHT 


of  a flexible  tube,  so  that  the  frame  may  be  moved 
about.  Where  possible  to  arrange,  this  is  highly  to  be 
recommended,  although  it  is  not  so  convenient  for 
home  portraiture  as  the  mercury -vapor  lamp.  Since 
the  Welsbach  light,  as  has  been  said,  is  relatively  richer 
in  red  rays  than  daylight,  good  color  values  may  be 
obtained  without  the  use  of  a filter. 

Flash-light. — In  many  cases  it  will  be  necessary 
to  employ  flash  powder,  and  generally  speaking  the 
compound  powders  are  preferable  to  powdered  mag- 
nesium, since  they  give  a more  intense  illumination  and 
much  less  smoke  and  dust.  Two  cautions  may  well  be 
given  to  the  worker,  the  first  being  that  the  compound 
powders  should  never  be  used  in  a closed  lamp  such  as 
is  employed  for  magnesium,  for  they  are  explosive  and 
if  detonated  in  a closed  space  a serious  explosion  may 
result.  They  should,  therefore,  in  all  cases  be  used  in 
an  open  pan  and  should  be  handled  with  the  same  care 
as  would  be  given  gunpowder,  being  preferably  fired 
from  a distance  by  means  of  electricity,  many  forms 
of  apparatus  being  available  for  this  purpose.  The 
second  caution  is  that  the  photographer  should  never 
attempt  to  make  his  own  flash  powder,  since  unless 
handled  with  knowledge  and  care  these  powders  may 
be  detonated  during  the  process  of  mixing.  It  will  be 
found  that  some  powders  give  greater  illumination  and 
less  smoke,  weight  for  weight,  than  others,  and  such 
are  of  course  to  be  preferred.  It  is  impossible  to  give 
definite  directions  as  to  the  amount  of  powder  to  be 
used  in  any  particular  circumstances,  since  this  of 
course  varies  with  the  plate,  diaphragm,  character  of 
the  subject,  distance  of  the  subject  from  the  flash  and 

273 


BY  ARTIFICIAL  LIGHT 


kind  of  powder  used.  Two  experiences  of  the  writer’s 
may,  however,  prove  helpful  and  they  are  as  follows: 
The  first  was  a bust  portrait  of  a single  individual,  the 
plate  was  a Standard  Orthonon,  the  lens  aperture  was 
F/7.5  and  1J4  grams  (about  22  grains)  of  powder  were 
used.  In  the  second  case  a large  gymnasium  crowded 
with  people  was  to  be  photographed  and  the  plate  was 
a Seed’s  L Ortho  Non-Halation.  The  lens  aperture 
was  F/16  and  30  grams  (about  1 ounce)  of  powder  were 
used.  In  each  case  the  plate  was  fully  exposed. 

For  portrait  work  flash  sheets  will  be  found  satis- 
factory provided  the  sitter  can  be  depended  on  not  to 
move,  since  these  require  about  one  second  to  bum 
instead  of  approximately  one-twentieth  second  as  is 
the  case  with  flash  powder.  It  is  claimed  that  sheets 
give  a broader  and  more  diffused  illumination  than 
powder,  but  the  writer  generally  prefers  powder,  since 
this  may  be  made  to  give  either  a concentrated  light 
or,  by  spreading  it  out  in  a long  train,  a broad  flare, 
and  is  thus  more  under  the  operator’s  control. 

Most  flash-light  portraits  show  a staring,  unnatural 
effect  in  the  eyes,  but  this  may  be  avoided,  the  effect  in 
question  arising  from  the  fact  that  the  worker,  prior  to 
setting  off  the  flash,  either  turns  low  or  extinguishes  all 
lights  in  the  room  so  that  the  sitter  either  closes  his 
eyes,  unconsciously  bracing  himself  against  the  nervous 
shock  of  the  flash,  or  else  opens  his  eyes  wide  to  see  as 
much  as  possible  by  the  dim  illumination  remaining.  In 
the  latter  case  the  pupils  of  the  eyes  dilate,  this  adding 
to  the  staring  effect.  If  the  ordinary  lights  remain 
turned  on  full  during  the  entire  time  of  making  the  expos- 
ure neither  of  these  undesirable  results  will  take  place 

276 


OTHER  ILLUMINANTS 


and  the  staring  effect  will  not  be  found  in  the  print. 
There  need  be  no  fear  that  the  lights  in  the  room  will 
have  any  bad  effect,  since  they  will  not  ordinarily  furnish 
enough  illumination  to  act  on  the  plate  during  the  brief 
time  that  the  lens  is  open. 

Other  Illuminants. — What  has  been  said  of  in- 
candescent gas  is,  broadly  speaking,  true  of  the  metallic 
filament  electric  light  and  is  to  some  extent  true  as 
well  of  the  ordinary  oil  lamp  and  of  the  carbon  filament 
electric,  since  these  give  good  color  values  without  the 
use  of  a filter.  However,  the  illumination  resulting 
from  these  sources  is  so  weak  that  exposures  must  be 
much  longer  than  with  other  types  of  lamp.  The 
writer  on  one  occasion  made  a bust  portrait  by  the 
light  of  a flat  wick  kerosene  lamp  about  three  feet  from 
the  sitter;  the  plate  was  a panchromatic,  the  lens  aper- 
ture was  F/6.8  and  the  exposure,  which  was  approxi- 
mately correct,  was  five  minutes.  With  a round  wick 
lamp  this  might  have  been  diminished  by  two-thirds. 
No  definite  instructions  can  be  given  for  photography 
by  street  lamps  or  by  theatrical  illumination,  although 
it  may  in  general  be  said  that  in  such  cases  the  use  of  a 
panchromatic  plate  is  advised,  since  much  briefer  expos- 
ures are  then  possible  than  with  the  ordinary  or  the  or- 
thochromatic  plate.  If  the  source  of  illumination  is  in- 
cluded in  the  picture  a non-halation  plate  should  be  used. 

When  it  is  possible  to  employ  the  large  Mazda  lamps 
as  can  often  be  done  in  studio  work,  these  will  be  found 
very  satisfactory.  The  writer  has  secured  fully  timed 
negatives  on  a fast  panchromatic  plate,  with  the  lens 
working  at  F/5.5,  in  one  or  two  seconds,  when  using  a 
1000-watt  Mazda,  with  a 500-watt  lamp  of  the  same 
type  as  a supplementary  illuminant. 


277 


CHAPTER  XIX 

MOTION  PICTURE  PHOTOGRAPHY 

The  term  which  we  frequently  hear  applied  to 
motion  pictures,  that  is,  moving  pictures,  is  a mis- 
nomer, since  the  picture  seen  on  the  screen  by  the 
observer  does  not  actually  move  but  is  as  station- 
ary as  any  print  may  be.  The  illusion  of  motion  is 
due  to  a phenomenon  known  as  the  persistence  of 
vision,  the  result  of  which  is  that  an  object  which  is 
observed  for  a small  fraction  of  time  and  then  is  sud- 
denly removed  from  the  spectator’s  range  of  vision 
apparently  continues  to  be  seen  for  an  appreciable  time 
after  ibis  removed,  the  retinal  image  not  fading  at  once. 
In  motion  picture  work  an  object  in  motion  is  photo- 
graphed and  a fraction  of  a second  later  is  photographed 
again,  when  it  obviously  will  have  moved  through  a 
short  space.  A fraction  of  a second  later  it  is  again 
photographed  in  a succeeding  phase  of  motion,  and 
so  on  for  as  long  as  may  be  necessary  to  show  the 
complete  movement.  From  this  series  of  negatives 
transparencies  are  made  on  a long  strip  of  film  and  are 
projected  in  sequence  on  the  screen.  The  observer 
fails  to  recognize  the  obscuring  of  one  phase  of  the 
motion  during  the  time  that  another  is  being  brought 
on  the  screen  and  thus  an  illusion  of  continuous  motion 
is  produced. 

In  practice  this  result  is  attained  as  follows:  A 

long  strip  of  film  is  so  arranged  that  it  may  be  wound 
past  the  lens  with  an  intermittent  motion.  During 

278 


FIG.  45 —EXTERIOR  OF  MOTION  PICTURE  CAMERA 


FIG.  46.— MECHANISM  OF  MOTION  PICTURE  CAMERA 


MECHANISM 


the  period  of  rest  the  shutter  is  opened  and  the  expo- 
sure made,  the  shutter  is  then  closed  and  the  film  is 
jerked  forward  a short  distance,  when  the  shutter  is 
opened  again  and  another  exposure  is  made  and  so  on 
for  as  long  as  it  may  be  desired  to  continue  the  opera- 
tion, within,  of  course,  the  limits  placed  by  the  amount 
of  film  which  it  is  possible  to  arrange  in  the  magazine 
of  the  camera.  Figure  45  shows  a typical  motion  pic- 
ture camera  and  Figure  46  shows  the  general  arrange- 
ment of  the  mechanism.  In  the  back  of  the  camera  are 
placed  two  retorts,  the  upper  one  carrying  the  unex- 
posed film.  From  this  retort  the  film  is  carried  through 
a velvet-lined  slit,  which  of  course  is  light-tight.  From 
this  it  passes  over  a sprocket,  being  formed  into  a loop 
the  purpose  of  which  is  to  insure  flexibility  of  motion 
and  to  prevent  dragging  of  the  film.  The  teeth  in  the 
sprocket  engage  in  perforations  along  the  edges  of  the 
film,  as  do  also  claws  which  operate  by  a cam,  the  claws 
serving  to  drag  the  film  forward  during  the  period 
when  the  shutter  is  closed.  The  film  passes  over  a 
small  plate  which  insures  contact  between  the  film  and 
the  gate,  the  latter  being  the  opening  behind  the  lens 
through  which  the  exposure  is  made.  After  leaving 
the  gate  the  film  is  formed  into  a second  loop  and  passes 
over  another  sprocket,  whence  it  is  wound  into  the 
retort  for  exposed  film  at  the  bottom  of  the  camera. 
The  shutter  is  in  the  form  of  a rotating  wheel  part  of 
which  has  been  cut  away  so  that  it  alternately  opens 
and  closes  the  lens.  The  entire  mechanism  is  operated 
by  a crank  and  the  customary  rate  at  which  the  crank 
is  turned  is  two  revolutions  per  second,  the  gearing 
being  so  adjusted  that  sixteen  exposures  per  second 

279 


MOTION  PICTURE  PHOTOGRAPHY 


are  made  on  the  film.  Since  the  standard  opening  of 
the  gate  is  one  inch  wide  by  three-fourths  inch  high  it 
will  be  seen  that  at  the  usual  rate  of  turning  the  crank 
one  foot  of  film  per  second  is  used,  so  that  a camera 
having  a retort  capacity  of  one  hundred  and  fifty  feet 
of  film  is  capable  of  continuous  operation  for  two  and 
a half  minutes  without  reloading  and  one  having  a 
retort  capacity  of  four  hundred  feet  of  film  may  be 
operated  for  approximately  six  and  a half  minutes. 

The  price  of  a motion  picture  camera  varies  as 
widely  as  with  the  case  of  ordinary  cameras,  the  ex- 
tremes of  cost  being  about  $25  and  $400,  the  higher 
priced  instrument  being  of  course  more  finely  made  and 
having  special  adjustments.  As  an  example  of  the 
latter  may  be  mentioned  the  shutter,  which  in  the 
cheaper  camera  consists  of  approximately  one-half  of 
a complete  disk  of  metal  so  that  the  exposure  is  neces- 
sarily one  thirty-second  of  a second  so  long  as  the  crank 
is  turned  at  the  normal  rate  of  speed,  whereas  the 
higher  priced  cameras  have  adjustable  shutters  so  that 
the  exposures  may  be  varied  considerably  from  this 
standard  in  case  the  light  or  the  speed  of  motion  of  the 
subject  requires  longer  or  shorter  exposure.  Also,  the 
more  expensive  cameras  have  often  a special  gearing 
so  adjusted  that  each  revolution  of  the  crank  makes 
one  exposure,  this  being  designed  for  the  production 
of  trick  pictures  or  for  photographing  exceedingly  slow 
motions,  such  as  the  growth  of  a plant,  when  the  ex- 
posures are  made  at  intervals  of  several  minutes  or 
perhaps  several  hours.  Of  course  the  photographer’s 
pocket-book  will  determine  to  a great  extent  the  make 
of  camera  which  he  will  use,  but  certain  fundamental 

280 


EXPOSURE 


desiderata  may  be  indicated.  The  camera  should  be 
provided  with  a balance  wheel  heavy  enough  to  insure 
even  and  regular  motion  of  the  crank,  since  it  is  not 
easy  to  turn  the  crank  with  perfect  regularity  until 
considerable  experience  has  been  gained.  The  lens 
should  be  of  the  fastest  type  obtainable,  a speed  of 
F/3.5  being  none  too  fast  for  poor  light  conditions, 
and  it  is  of  course  always  possible  to  stop  down  when 
the  quantity  of  light  would  mean  excessive  exposure 
at  full  aperture.  The  mechanism  should  be  so  designed 
that  it  is  easy  to  thread  the  film  through  the  sprockets 
and  the  gate  rapidly,  and  it  is  of  course  as  necessary 
with  this  camera  as  with  any  other  that  the  box  be 
light-tight.  The  gearing  should  be  positive  in  its  ac- 
tion and  not  likely  to  slip,  and  if  the  camera  is  to  be 
carried  about  from  place  to  place,  it  should  be  as  light 
as  possible.  The  tripod  should  be  substantial  and 
rigid,  this  being  even  more  necessary  than  in  ordinary 
photography,  since  the  strain  put  on  it  by  the  turning 
of  the  crank  is  much  greater  than  in  the  case  of  or- 
dinary still  work. 

Exposure. — The  film  having  been  threaded  up  and 
the  camera  set  up  on  the  tripod,  it  becomes  necessary 
to  determine  the  proper  exposure.  Of  course  if  the 
shutter  is  of  the  type  having  a fixed  opening,  the  only 
variation  possible  is  that  due  to  opening  or  closing  the 
diaphragm  of  the  lens,  and  the  same  factors  which 
control  the  question  of  diaphragm  and  exposure  in  or- 
dinary photography  are  equally  operative  here,  so  that 
the  Burroughs  Wellcome  note-book  may  be  used  for 
this  purpose,  simply  bearing  in  mind  that  in  this  case 
it  is  the  exposure  which  is  fixed  and  the  diaphragm 

281 


MOTION  PICTURE  PHOTOGRAPHY 


which  varies.  It  will  be  found  that  for  many  classes 
of  subject  a lens  working  at  F/3.5  will  allow  the  pas- 
sage of  sufficient  light  to  permit  of  using  a three  times 
or  a five  times  ray-filter,  and  as  a rule  this  should  be 
done  whenever  possible,  since  better  values  are  thus 
obtained  and  the  pictures  are  more  convincing.  For 
indoor  work  this,  however,  will  rarely  be  possible. 
When  the  exposure  and  the  diaphragm  have  been  deter- 
mined, the  next  step  is  to  focus  on  the  subject,  and  this 
is  done  in  one  of  two  ways.  Some  lenses  are  provided 
with  a scale  so  that  focussing  is  done  in  the  same  man- 
ner as  with  the  folding  film  camera;  that  is,  by  estimating 
the  distance  from  the  camera  to  the  subject  and  setting 
the  lens  the  proper  distance  from  the  film.  Other  instru- 
ments, however,  have  a focussing  tube  extending  from 
the  back  of  the  camera  to  the  gate,  through  which  the 
operator  may  look  to  see  whether  or  not  the  image  is 
accurately  focussed  on  the  film,  a magnifying  lens 
usually  being  placed  in  the  tube  to  increase  the  apparent 
size  of  the  image.  When  the  focussing  has  been  satis- 
factorily completed  and  everything  is  prepared  the 
crank  should  be  given  a few  turns  to  insure  that  all  the 
film  which  was  exposed  to  light  during  the  threading 
up  has  been  wound  past  the  gate,  and  exposure  may 
then  be  begun.  The  crank  should  be  turned  regularly 
and  steadily  at  the  rate  of  two  revolutions  per  second 
until  the  desired  length  of  film  has  been  exposed,  which 
point  is  shown  either  by  the  desired  amount  of  motion 
having  been  photographed,  by  a film  indicator  which  is 
provided  with  the  better  cameras,  or  by  the  fact  of 
the  operator’s  having  counted  the  desired  number  of 
feet,  which  may  easily  be  done  by  remembering  that 
282 


EXPOSURE 


two  turns  of  the  crank  expose  one  foot  of  film.  Some 
cameras,  indeed,  are  provided  with  small  electric 
motors  operated  by  dry  batteries,  or  with  compressed 
air  motors,  the  cylinders  being  filled  with  air  by  means 
of  a bicycle  pump,  and  this  type  of  camera  is  exceed- 
ingly valuable  in  natural  history  work  or  work  in  un- 
usual locations  where  a tripod  cannot  be  employed, 
since  an  instrument  of  this  kind  can  be  used  in  the  hand 
after  the  manner  of  a Graflex  or  Kodak.  Such  instru- 
ments, however,  are  necessarily  expensive,  and  the 
standard  motion  picture  camera  is  operated  by  means 
of  a hand  crank.  When  the  desired  amount  of  film  has 
been  exposed  the  motion  of  the  crank  is  stopped  and 
the  remainder  of  the  film  can  be  exposed  on  some  differ- 
ent subject,  or  if  desired  the  film  can  be  cut  and  the 
retort  containing  the  exposed  film  be  replaced  by  an 
empty  one,  the  remainder  of  the  film  being  threaded 
up  and  further  exposure  being  made  at  some  subse- 
quent time.  This  is  done  when  it  is  necessary  to  develop 
the  exposed  portion  of  the  film  at  once,  as  in  topical  or 
news  work. 

When  the  retort  for  unexposed  film  is  empty  it  may 
be  shifted  to  the  lower  position  in  the  camera,  thus 
preparing  it  for  the  reception  of  exposed  film,  a loaded 
retort  taking  its  place  above. 

During  the  time  of  exposure  the  subject  should  be 
watched  in  the  view-finder,  which  may  be  either  the 
direct  type  consisting  of  a negative  lens  with  a sighting 
rod,  or  may  be  the  box  type  familiar  to  everyone  who 
has  used  a folding  film  camera.  Choice  between  these 
types  is  purely  a matter  of  individual  preference,  some 

finding  it  easier  to  manipulate  the  crank  while  follow- 

283 


MOTION  PICTURE  PHOTOGRAPHY 


ing  the  subject  in  one  type  than  is  the  case  with  the 
other. 

Tripods  having  what  is  known  as  a panoramic  and 
tilting  top  are  obtainable,  the  top  of  the  tripod  being 
arranged  in  such  fashion  that  by  turning  a crank  the 
camera  may  be  tilted  either  up  or  down,  and  turning 
another  crank  rotates  it  about  a vertical  axis.  This 
form  of  tripod  is  very  convenient  for  many  purposes 
and  is  in  general  use  by  professionals,  but  for  amateurs’ 
use  it  will  seldom  be  required  and  is  unnecessarily 
expensive. 

Development. — For  developing  the  exposed  film 
the  most  approved  arrangement  is  a frame  like  that 
shown  in  Figure  47.  This  may  be  made  of  light  wood 
by  any  carpenter  or  by  the  photographer  himself,  and 
should  be  soaked  for  an  hour  or  so  in  melted  paraffine, 
drained,  and  allowed  to  dry  before  use.  The  end  pieces 
should  be  round,  the  movable  one,  however,  having 
square  ends,  and  a row  of  small  brads  should  be  driven 
into  each,  as  indicated  in  the  sketch,  to  keep  the  sec- 
tions of  the  film  separated.  If  one  end  of  each  of  the 
side  pieces  is  slotted  and  furnished  with  a helical  spring 
so  as  to  put  a slight  tension  on  the  film  after  it  is  wound 
on  the  frame  this  frame  may  be  used  for  drying  as  well 
as  for  developing  and  fixing,  hooks  on  the  side  pieces 
serving  to  keep  the  end  piece  in  its  retracted  position 
while  the  film  is  being  wound  on  the  frame.  It  is,  how- 
ever, better  to  wind  the  film  off  on  a drum  about  three 
or  four  feet  in  diameter  and  five  feet  long  to  dry,  since 
by  this  means  sharp  bends  in  the  film  are  avoided.  To 
develop  the  film  the  retort  is  taken  into  the  dark  room 
and  the  free  end  of  the  film  is  fastened  to  one  of  the 

284 


DEVELOPMENT 


end  pieces  of  the  developing  frame  by  means  of  a thumb- 
tack or  a push-pin.  The  film  is  then  wound  on  the 
frame,  the  latter  being  rotated  on  its  trunnions  as  the 
film  is  drawn  from  the  retort.  When  all  the  film  has 
been  wound  on  the  frame,  emulsion  side  out,  of  course, 
the  end  is  fastened  by  means  of  another  pin,  the  frame 
is  lifted  from  the  stand  and  is  lowered  into  the  tank  of 
developer.  In  winding  the  film  on  the  frame  it  is  ad- 


Fig.  47. 


vised  to  draw  it  from  the  retort  as  it  is  wound,  since  if 
the  film  is  taken  from  the  retort  and  allowed  to  lie 
loose  on  the  table  or  work-bench  it  is  apt  to  kink  and 
become  unmanageable. 

The  developing,  fixing,  and  washing  tanks  should 
be  so  arranged  that  the  developing  frame  may  be  placed 
in  them  vertically  and  they  should  be  furnished  with 
guides  to  support  the  ends  of  the  frame  and  keep  the 

285 


MOTION  PICTURE  PHOTOGRAPHY 


film  from  touching  the  sides  of  the  tank.  These  tanks 
may  be  made  of  wood  and  should  be  well  coated  inside 
with  paraffine.  Three  will  be  needed,  each  of  them  three 
or  four  inches  deeper  than  the  frame  and  perhaps  four 
inches  wide. 

The  same  laws  which  govern  the  exposure  and  de- 
velopment of  any  plate  or  film  apply  also  to  motion 
picture  work,  and  any  developer  which  the  photog- 
rapher prefers  may  be  used  for  this  purpose.  It  should 
be  observed,  however,  that  much  of  the  professional 
motion  picture  work  shows  over-development  of  either 
the  negative  or  the  positive  film,  and  not  infrequently 
under-exposure  is  in  evidence  as  well.  There  is  no 
reason  why  motion  picture  work  should  not  be  treated 
in  a high  key  when  the  aim  is  pictorial,  although  it 
seems  to  be  the  case  that  a film  handled  in  a low  key 
is  not  apt  to  be  so  effective  as  is  the  case  with  a print. 
Should  the  negative  film  be  incorrectly  exposed  or  de- 
veloped, it  will  be  found  advisable  to  correct  these  errors 
at  the  time  of  printing  rather  than  to  attempt  either 
intensification  or  reduction. 

Development  may,  of  course,  be  either  by  inspection 
or  by  time,  but  whichever  method  is  used  the  develop- 
ing frame  should  be  turned  end  for  end  several  times 
in  the  tank  in  order  to  prevent  uneven  development. 
When  development  is  complete  the  film  is  fixed  for  the 
proper  length  of  time  in  the  fixing  tank  and  is  then 
transferred  to  the  washing  tank.  The  remarks  as  to  fix- 
ing and  washing,  especially  with  regard  to  having  the 
inflow  of  water  at  the  top  of  the  washing  tank  and 
the  outflow  at  the  bottom,  apply  to  motion  picture 
films  as  well  as  to  ordinary  photographic  work. 

286 


PRINTING 


Drying. — After  the  film  is  washed  it  may  be  wound 
off  the  developing  frame  to  the  drying  drum,  which 
latter  should  be  supported  on  trunnions  or  an  axle,  and 
is  then  set  aside  in  a dry  room  free  from  dust.  It  is  not 
advised  to  dry  the  film  in  the  dark  room,  both  because 
the  atmosphere  in  the  latter  is  likely  to  be  damp  and 
because  there  are  apt  to  be  particles  of  chemical  dust 
floating  in  the  air,  it  being  even  more  important  to 
keep  the  film  free  from  dust  and  spots  than  is  the  case 
with  ordinary  photography,  since  pin-holes  are  difficult 
to  spot  on  a motion  picture  film,  and  if  not  spotted 
show  very  conspicuously  on  the  screen. 

Printing.— Printing  is  done  on  a strip  of  film 
similar  to  that  used  for  the  negative  except  that  the 
emulsion  is  much  slower.  There  are  many  forms  of 
printers  on  the  market,  some  manufacturers  arranging 
their  cameras  so  that  by  the  use  of  an  additional  bracket 
the  camera  itself  may  be  used  for  printing.  The  main 
points  in  printing  are  to  keep  the  positive  and  negative 
films  in  contact,  to  draw  them  at  a uniform  rate  of  speed 
past  a constant  illumination,  and  to  adjust  this  rate 
of  speed  so  that  the  positive  film  receives  the  proper 
exposure.  Until  considerable  experience  has  been 
gained  it  will  be  well  to  print  a few  test  slips  of  a foot 
or  so  of  film,  developing  and  fixing  these  in  order  to 
determine  whether  or  not  the  exposure  has  been  cor- 
rect. Some  printers  have  simply  a sprocket  wheel  the 
teeth  of  which  engage  the  perforations  in  both  films, 
thus  drawing  the  films  through  the  gate  in  front  of  the 
light  with  a uniform  motion;  whereas  others  are  fitted 
with  a claw  and  cam  which  draws  the  films  through  in 
a series  of  jerks,  as  is  done  in  making  the  original  nega- 

287 


MOTION  PICTURE  PHOTOGRAPHY 


tive.  There  seems  to  be  no  choice  between  these  dif- 
ferent types  so  far  as  results  are  concerned,  the  only 
difference  being  in  the  worker’s  personal  preference. 
The  subsequent  operations  on  the  positive  film  are 
identical  with  those  on  the  negative  film. 

Toning  the  Positive. — For  special  effects,  such  as 
sunlight,  moonlight,  firelight,  etc.,  it  will  often  be  found 
desirable  to  stain  or  tone  the  positive  film,  and  many  for- 
mulae for  this  work  can  be  found  in  the  photographic 
annuals,  the  formulae  given  for  use  with  bromide  papers 
being  applicable  to  motion  picture  film  as  well. 

General  Remarks. — Many  curious  phenomena  are 
observable  in  motion  picture  work.  For  example,  a 
wheel  may  sometimes  appear  to  be  revolving  backward 
instead  of  forward,  the  cause  of  this  being  that  succes- 
sive phases  of  the  motion  are  photographed  slightly 
before  a given  spoke  has  reached  the  position  occupied 
by  its  predecessor  when  photographing  the  first  phase. 
Thus  if  we  consider  a wheel  having,  say,  but  four 
spokes  and  if  the  first  phase  is  photographed,  the  sec- 
ond phase  being  photographed  at  such  an  interval 
thereafter  that  the  wheel  has  moved  through  an  angle 
of  90°,  and  so  on,  it  will  be  apparent  that  the  wheel 
will  seem  to  be  standing  still.  Similarly,  if  the  different 
phases  are  photographed  at  such  an  interval  that  the 
wheel  rotates  through,  say,  85°,  it  will  of  course  appear 
to  be  revolving  backward,  and  for  it  to  show  its  true 
motion  it  is  necessary  that  it  revolve  through  slightly 
more  than  90°  during  the  interval  between  the  photo- 
graphing of  successive  phases. 

In  many  cases  the  motion  of  the  subject  is  such 
that  a standard  speed  of  sixteen  pictures  per  second  is  in- 

288 


GENERAL  REMARKS 


sufficient  to  secure  a smooth  and  easy  motion  in  the  result, 
this  being  due  to  the  circumstance  that  a considerable 
portion  of  each  phase  takes  place  during  the  time  that 
the  shutter  is  closed.  Thus,  a man  walking  at  the  rate 
of  four  miles  an  hour,  which  is  an  average  gait,  will 
appear  to  move  in  a jerky  fashion  like  an  automaton. 
In  such  cases  the  taking  speed  should  be  more  rapid, 
and  this  may  be  secured  by  turning  the  crank  of  the 
camera  faster.  It  has  also  been  found  that  the  result 
is  much  better  in  general  if  the  taking  speed  is  made 
from  twenty  to  twenty -four  pictures  per  second  instead 
of  sixteen,  and  it  is  not  improbable  that  in  the  near 
future  some  such  speed  will  be  adopted  for  general  use, 
though  it  would  involve  from  25  per  cent,  to  50  per 
cent,  increase  in  the  cost  of  the  film  used,  and  would 
mean  changing  the  gearing  on  cameras  to  be  used  at  the 
higher  rate  of  speed. 

Any  amateur  with  patience  can  produce  many  in- 
teresting films  by  photographing  slow  motions  at  wide 
intervals;  thus  the  growth  of  a plant  may  be  photo- 
graphed from  the  time  that  it  first  appears  above  the 
ground  until  the  completion  of  the  expanding  of  the 
bloom.  To  do  this  it  is  necessary  to  illuminate  the  sub- 
ject by  artificial  light,  since  the  picture  must  be  taken 
at  regular  intervals  throughout  the  twenty-four  hours 
of  the  day,  and  a special  spindle  must  be  fitted  which 
permits  of  making  one  exposure  to  each  turn  of  the 
crank.  The  plant  is  photographed  at  intervals  of  from 
several  minutes  to  several  hours,  depending  on  the  rate 
of  growth,  and  when  this  series  of  exposures  is  printed 
and  projected  upon  the  screen  the  projection  may  oc- 
cupy one  or  two  minutes,  the  entire  development  of 

19  289 


MOTION  PICTURE  PHOTOGRAPHY 


the  plant  being  seen  in  that  time.  For  this  type  of  work 
much  depends  on  the  determination  of  the  correct 
interval  for  photographing  successive  phases  of  the 
motion,  since  if  this  is  not  determined  carefully  the 
result  will  seem  jerky  and  disjointed.  It  is  also  pos- 
sible to  photograph  extremely  rapid  motions,  such  as 
the  flight  of  a bullet,  and  to  slow  down  the  motion  in 
projecting,  thus  causing  the  rapidly  moving  object  to 
complete  its  travel  in  perhaps  one  or  two  minutes  on 
the  screen,  whereas  actually  the  motion  across  the  space 
in  front  of  the  camera  may  have  occupied  not  more  than 
one  three-hundredth  or  one  four-hundredth  of  a second. 
This  type  of  work,  however,  demands  apparatus  which 
is  beyond  the  reach  of  the  average  amateur. 

There  seems  to  be  no  reason  why  motion  picture 
work  should  not  be  fully  as  meritorious  from  an  artistic 
standpoint  as  the  ordinary  still  photography,  although 
it  must  be  admitted  that  up  to  the  present  time  this 
ideal  has  not  been  realized,  most  producers  being  in- 
tent on  securing  films  which  will  be  sufficiently  sensa- 
tional in  character  to  attract  large  crowds  and  be  finan- 
cially profitable.  Unquestionably  they  have  been  tre- 
mendously successful  in  this  respect,  as  is  evidenced  by 
the  great  sums  which  are  spent  on  the  production  of 
photoplay  films,  such  expenditure  being  without  justi- 
fication unless  anticipated  and  actual  receipts  were 
correspondingly  large.  Still,  it  is  more  than  probable 
that  at  some  future  date  there  will  arise  a producer  who 
will  subordinate  the  sensational  to  the  meritorious,  and 
the  reward  of  such  an  individual  will  be  large.  At  least 
one  man  is  now  working  along  these  lines  and  has 
produced  some  wonderfully  fine  films. 

290 


GENERAL  REMARKS 


Many  persons  feel  that  the  photoplay  is  destined 
to  supplant  the  legitimate  drama,  but  the  writer  does 
not  believe  that  this  can  ever  take  place,  since  the 
motion  picture  film  appeals  to  the  eye  alone  and  is 
therefore  limited  to  a comparatively  low  grade  of  in- 
tellectual appeal  and  to  a crude  emotional  stimulus. 
The  drama,  on  the  other  hand,  appeals  to  both  the  eye 
and  the  ear,  and  since  it  places  actual  individuals  before 
the  spectator  an  appeal  not  only  through  muscular  and 
facial  expression  but  through  the  ear  as  well  is  made, 
the  spoken  word  being  a far  more  potent  factor  in 
stimulating  an  emotional  response  than  is  the  case  with 
the  eye.  Should  the  reader  be  inclined  to  doubt  this, 
let  him  try  to  imagine  any  photoplay  which  would  be 
capable  of  arousing  the  feelings  stimulated  by  the 
quarrel  between  Brutus  and  Cassius  in  Julius  Caesar, 
or  by  the  Council  of  Infernal  Peers  in  Paradise  Lost, 
and  it  will  be  seen  that  the  photoplay  is  totally  in- 
capable of  rising  to  the  emotional  heights  possible  to 
the  spoken  word. 


CHAPTER  XX 
CONCLUSION 

The  effort  has  been  made,  so  far  as  is  possible  in  a 
book  the  size  of  the  present  one,  to  give  a discussion 
of  the  general  principles  of  the  various  methods  which 
will  be  found  most  useful  to  the  person  who  wishes  to 
express  artistic  impulses  by  means  of  the  camera,  but 
it  has  not  been  possible  to  give  a complete  discussion 
of  all  the  photographic  methods  which  will  be  of  value 
to  such  a worker,  since  to  do  so  would  require  several 
volumes  the  size  of  this  one,  and,  as  was  stated  in  the 
foreword,  no  reference  has  been  made  to  the  many 
technical  methods  employed  in  commercial  work.  It 
must  not,  however,  be  supposed  that  the  photographer 
can  become  a pictorialist  of  the  first  rank  merely 
through  familiarity  with  technical  methods.  The  aim 
of  the  artist  must  always  be  to  arouse  in  those  looking 
at  his  work  some  emotional  mood  or  sentiment,  and  to 
accomplish  this  other  qualities  are  required  beside  per- 
fect technique.  The  finished  picture  may  be  likened 
to  the  human  being,  who  requires  for  perfect  balance 
the  three  qualities  of  body,  mind  and  spirit,  being 
incomplete  unless  all  three  of  these  characteristics 
exist  in  due  and  suitable  proportions.  In  pictorial  art 
technique,  which  is  purely  objective,  may  be  likened  to 
the  body;  composition  of  line  and  value,  being  more 
subjective,  may  fitly  be  compared  to  the  mind;  and  the 
spirit  of  the  human  being  finds  its  counterpart  in  the 
292 


STUDY  OF  COMPOSITION 


expressive  impulse  underlying  the  choice  of  subject  and 
the  manner  of  its  treatment.  Many  workers  of  the 
present  day,  both  painters  and  photographers,  are  con- 
tent to  produce  a pleasing  arrangement  and  perfect 
technique,  feeling  that  a well-expressed  esthetic  design 
is  all  that  is  necessary  for  the  production  of  a finished 
work  of  art.  Referring  to  our  analogy,  however,  it  will 
be  seen  that  such  a picture  may  fitly  be  compared  to  the 
hedonist,  who,  however  perfect  physically  and  intel- 
lectually, can  never  leave  a lasting  impression  on  his 
time  for  lack  of  a high  spiritual  motive,  and  pictures 
of  this  nature  can  have  only  an  ephemeral  value,  how- 
ever pleasing  they  may  be  esthetically. 

The  study  of  composition  is  beyond  the  scope  of 
the  present  book,  but  many  works  on  the  subject  exist 
and  there  is  every  facility  offered  to  the  student  for 
acquiring  skill  in  this  necessary  element  of  art.  It 
may  be  said  that  in  general  more  can  be  learned  from 
a careful  study  of  black-and-white  reproductions  from 
the  works  of  great  artists  than  from  the  study  of  any 
book,  since  the  principles  of  composition  are  merely 
verbal  enunciations  of  certain  arrangements  which  past 
experience  has  found  pleasing,  and  a sense  of  composi- 
tion must  be  so  thoroughly  ingrained  in  the  worker 
that  its  expression  will  result  without  conscious 
effort. 

The  third  quality,  that  of  spirit,  cannot  be  taught, 
but  must  result  from  an  inherent  desire  to  do  work  of 
an  ennobling  character.  Even  this  quality,  however, 
may  be  developed  or  may  be  suppressed,  and  the  devel- 
opment or  suppression  of  a lofty  desire  is  to  a great 
extent  dependent  on  surrounding  circumstances.  It 

293 


CONCLUSION 


is  well  known  that  a high  order  of  mediocrity,  in  many 
cases  but  slightly  separated  from  actual  genius,  may 
result  from  careful  and  persistent  study  and  effort,  but 
it  is  not  so  well  known  that  true  genius  may  be  sup- 
pressed. There  is  in  the  minds  of  many  persons  a 
belief  that  genius  will  always  show  itself,  but  this  is 
far  from  being  the  case,  since  great  genius  may  be  pre- 
vented from  finding  expression  through  the  necessity 
of  producing  a relatively  low  order  of  work  to  supply  a 
commercial  demand  and  may  also  in  many  instances  be 
vitiated  by  unfavorable  personal  surroundings;  but  it 
must  not  be  supposed  from  this  that  the  writer  has  any 
sympathy  whatever  with  the  so-called  artistic  tempera- 
ment, which  he  believes  to  be  merely  an  excuse  for  the 
artist  to  employ  mannerisms  or  self-indulgences  which 
would  not  be  tolerated  in  the  average  individual.  It 
will  in  general  be  found  that  artists  of  the  first  rank  do 
not  possess  the  “artistic  temperament,”  but  in  the 
affairs  of  daily  life  conduct  themselves  quite  as  well  as 
those  individuals  whose  work  is  not  of  an  artistic  na- 
ture. On  the  other  hand,  suitable  encouragement  favors 
the  development  of  genius,  and  where  any  spark  of 
this  exists  it  may  be  fostered  by  proper  educational 
means.  Unfortunately,  the  standard  education  of  this 
country  at  the  present  time  is  designed  to  reduce  all 
individuals  to  a common  level,  and  it  is  to  be  hoped  that 
the  next  few  years  will  see  a decided  improvement  in 
this  respect,  signs  of  such  a change  not  being  wanting 
at  present. 

The  highest  development  of  genius  in  any  branch 
of  human  activity  can  result  only  from  the  combina- 
tion of  a peculiar  mentality  with  long  and  arduous 

294 


COMMERCIAL  CONDITIONS 

study  and  effort,  but  it  is  by  no  means  impossible  for 
workers  who  lack  the  inherent  gift  of  genius  to  produce 
artistic  results  of  a pleasing  nature  and  of  a very  high 
level,  works  which  will  be  helpful  to  many  persons  to 
whom  the  highest  productions  would  be  of  no  value 
whatever.  A certain  degree  of  development  is  neces- 
sary to  permit  one  to  appreciate  and  benefit  by  any 
given  work,  and  consequently  the  finest  works  of  art 
can  appeal  only  to  those  who  are  prepared  to  under- 
stand them,  this  class  of  course  increasing  as  the  devel- 
opment of  the  race  progresses.  Therefore  no  worker 
who  finds  himself  lacking  in  great  genius  should  despair 
of  serving  his  fellow  men,  since  he  will  always  find  an 
audience  and  this  audience  will  always  be  helped  spirit- 
ually if  the  artist’s  original  purpose  was  a noble  one. 
Everyone  who  feels  any  artistic  impulse  whatever 
should  follow  the  direction  in  which  it  leads  and  may 
be  sure  that  if  he  does  so  he  is  aiding  the  progress  of 
the  race. 

Many  workers  are  so  limited  by  commercial  condi- 
tions that  they  can  give  but  a small  portion  of  their 
time  to  the  study  and  practice  of  art,  and  these  are 
advised  to  adopt  some  one  method  of  work  and  to 
adhere  to  it  throughout,  since  a perfect  knowledge  of 
all  technical  methods  involves  so  great  an  amount  of 
study  as  to  be  prohibitive  to  one  whose  time  cannot 
be  given  entirely  to  this  work.  Photographers  who  are 
thus  restricted  are  advised  to  employ  a double-coated 
orthochromatic  or  a backed  panchromatic  plate  and  to 
familiarize  themselves  with  the  use  of  platinum  and 
gum-platinum  or  of  oil  for  printing,  since  these 
methods  are  of  wider  application  than  any  other  and 

295 


CONCLUSION 

in  addition  are  about  the  easiest  for  the  worker  to 
learn  thoroughly. 

The  writer  hopes  that  this  book  may  prove  of  value 
to  students  of  photography,  and  is  confident  that  any- 
one who  will  devote  himself  with  enthusiasm  to  the  use 
of  the  camera  cannot  fail  to  produce  pictures  which  in 
addition  to  affording  gratification  to  the  worker  him- 
self will  also  prove  pleasing  in  some  degree  to  all  who 
are  interested  in  graphic  art. 

APPENDIX 

Since  Chapter  X was  written,  commercial  platinum 
paper  has  practically  disappeared  from  the  market, 
owing  to  the  use  of  this  metal  for  military  purposes, 
and  its  place  has  been  taken  by  a paper  in  which  the 
salts  of  palladium  are  employed,  palladium  being  one 
of  the  rare  platinum  group  of  elements.  There  seems 
no  reason  to  doubt  that  palladium  paper  will  give  prints 
fully  as  permanent  as  those  made  with  platinum,  and 
though  the  writer  has  not  had  opportunity  to  experi- 
ment extensively  with  the  new  product,  it  seems  quite 
on  a par  with  the  older  paper  as  regards  quality  and 
convenience.  The  developer  is  furnished  by  the  manu- 
facturers of  the  paper  and  the  clearing  bath  consists 
merely  of  equal  parts  of  the  developing  solution  and 
water,  the  handling  of  the  paper  being  in  other  respects 
the  same  as  that  of  platinum.  Palladium  paper  is 
furnished  in  smooth  and  rough  white  stock,  and  smooth 
buff,  and  is  strongly  to  be  recommended  to  those  plati- 
num workers  who  have  found  themselves  unable  to 
secure  their  favorite  printing  medium. 

296 


INDEX 


Aberration,  chromatic,  31 
spherical,  31 
Actinometers,  92 
Angstrom  unit,  30 
Art,  in  motion-picture  photog- 
raphy, 290 
purpose  of,  292 

Artificial  light,  photographing  hy, 
flashlight,  275 
flash  sheets,  276 
incandescent  gas,  274 
kerosene  lamp,  277 
mercury  vapor  arc,  273 
Astigmatism,  37 

Autochrome  process,  correcting 
errors  of  exposure,  258 
desensitizing,  259 
failures,  260 
frilling,  260 

intensification  and  reduc- 
tion, 261 

latitude  of  exposure,  257 
reversing  solution,  for- 
mula, 259 
speed  of  plate,  263 
theory,  256 

Backing,  see  halation 
Bichromate  poisoning,  163 
Blanchard  brush,  164 
Box  camera,  20 
Bromide  enlarging,  124 
Bromide  paper  for  negatives,  74, 
120 

Bromoil,  see  oil 

Camera,  the  adjustments,  17-20 
types,  20-23 


Carbon,  advantages  and  disad- 
vantages, 139 
bichromate  poisoning,  163 
clearing  bath,  172 
continuing  action  of  light, 
169 

failures,  176 
keeping  qualities,  162 
making  transfer  paper,  166 
quick-drying  sensitizer,  163 
registration  in  multiple  print- 
ing, 174 

relative  speed  and  scale  of 
different  tissues,  178 
safe-edge,  165 

sensitizing  by  immersion,  T61 
theory,  160 
timing  exposure,  164 
transferring,  165,  166,  169 
Characteristic  curve  of  plate,  77 
Chromatic  aberration,  31 
Circle  of  confusion,  39 
Color,  autochrome  process,  256 
desirability  of  color  in  pho- 
tography, 135,  251 
effect  of,  on  nervous  system, 
253 

function  of,  in  art,  254 
Hess-Ives  process,  256,  263 
modifications  of  color,  in  bro- 
mide, 125,  127 
in  carbon,  139,  161, 
173 

in  gum,  140,  183,  270 
in  oil  and  bromoil, 
142 

in  photogravure,  143, 
242,  247 

in  platinum,  138, 150, 
151,  153 


297 


INDEX 


Color,  modifications  of,  in  the 
ideal  medium,  135 
multi-color  gum,  270 
Paget  process,  256,  261 
Sanger-Shepherd  process, 
256 

three-color  carbon,  256,  265 
three-color  gum,  256,  265 
value  of  color  in  science,  251 
Color  sensitiveness,  anti-screen 
plate,  60 

ordinary  plate,  57 
orthochromatic  plate,  59 
panchromatic  plate,  59 
percentages,  60 
visual,  57 

Combination  printing,  112 
Comet  marks,  see  platinum 
Condensing  lenses,  118,  119 
Continuing  action  of  light,  169, 
190,  216 

Contrast,  total,  modifications  of, 
by  increase  of 
printing  time,  136 
by  development,  79, 
82 

by  intensification, 
101 

by  multiple  printing, 
139,  140,  142,  173, 
194,  209,  247 
in  carbon,  139,  162, 
173 

in  gum,  140,  185, 
194 

in  gum-platinum,  209 
in  oil  and  bromoil, 
142,  214,  215,  217, 
220,  221,  223,  224 
in  photogravure,  143, 
240,  242,  245,  247 
in  platinum,  138, 139, 
148,  156,  159 
in  the  ideal  medium, 
130 

Curvature  of  the  field,  33 


Depth  of  field,  42 
Depth  of  focus,  42 
Developer,  the,  characteristics  of 
various  developers,  88 
factors  of  various  developers, 
85 

formulae  for  compounding, 
89,  90,  91 

function  and  composition, 
83 

platinum,  146 
Developing  tanks,  96 
Development  marks  in  platinum, 
147 

Development,  methods,  factorial, 
84 

inspection,  84 
tank,  87 
time,  86 

over-  and  under-,  character- 
istics of,  80,  82 

Diaphragms,  systems  of  marking, 
43 

types,  41 

use  of,  to  correct  for  optical 
errors,  41 

to  improve  definition,  42 
to  increase  depth  of  defi- 
nition, 42 

Dispersion  of  light,  see  light 
Distortion,  35 

Enlarging,  daylight  or  artificial 
light,  118 

glass  or  paper  negatives, 
120 

reasons  for,  115 
reasons  for  making  enlarged 
negatives,  116 
Enlarging  back,  120 
Exposure,  determination  of  cor- 
rect exposure,  92 
faulty,  symptoms  of,  82 
treatment  of,  81 
over-  and  under-,  character- 
istics of,  77  et  seq. 
meters  and  tables,  92 


298 


INDEX 


Factorial  development,  84 
Factors,  development,  table  of,  85 
Films,  advantages  and  disadvan- 
tages, 74 
Fixing  boxes,  96 
Flare,  34 

Flash-light,  photographing  by, 
275,  276 

Focal  length  of  lens,  best  for 
general  use,  48 
definition,  28 
relation  to  perspec- 
tive, 46 

to  determine,  29 
Folding  film  camera,  21 
Folding  hand  camera,  22 
Formation  of  an  image  by  a lens, 
28 

Gum,  actinometer,  to  make,  198 
method  of  use,  201 
advantages  and  disadvan- 
tages, 140 

best  type  of  negative,  197 
blending  brush,  184 

manner  of  use,  188 
coating  damp  paper,  189 
continuing  action  of  light,  190 
contrast,  variations  of,  140, 
185,  194 
failures,  203 

keeping  qualities  of  paper, 
205 

multi-color  work,  270 
papers  for  coating,  182 
pigment's,  183 

printing  speed  of  various 
colors,  190 

proportions  of  pigment  to 
gum,  185 

registration  in  multiple  print- 
ing, 195 

sizing,  temporary,  185 
permanent,  185 
stippling,  181,  189 


Gum,  stock  solutions,  gum,  182 
sensitizer,  182 
three-color  work,  265 
theory,  181, 

Gum-platinum,  advantages  and 
disadvantages,  141 
chief  value,  208 
registration,  207 
sizing,  206 

Halation,  definition,  70 

methods  of  preventing,  71 
Hess-Ives  process,  chief  disad- 
vantage, 265 

modification  of  results,  264 
power  of  duplication,  264 
speed  of  plates,  263 
theory,  256 

Hurter  and  Driffield,  77 
law,  80 

failure  of  law,  80 

Image,  formation  of,  by  a lens,  28 
Incandescent  gas,  photographing 
by,  274 

Intellectual  appeal  of  photog- 
raphy, 254 
Intensification,  101 

mercuric  bromide  intensifier, 
102 

mercuric  iodide  intensifier, 
103 

for  correcting  errors  of  ex- 
posure, 102 

Kerosene  lamp,  photographing 
by,  277 

Lens,  the  apochromat,  39 
anastigmat,  38 
periscopic,  39 
Petzval  portrait,  39 
rapid  rectilinear,  38 
single  achromatic,  37 
single  combination,  use  of,  45 


299 


INDEX 


Lens,  single  meniscus,  37 

soft  focus,  apparent  depth  of 
definition,  42 
discussion  of,  52 
pin-hole,  48 
Pinkham,  38 
Spencer  Port-Land,  38 
Struss,  31,  38,  39 
Wollensak  Verito,  38 
speeds  of  various  types,  45 
Light,  dispersion  of,  30 
refraction  of,  25 
wave  length  of,  25,  30 
wave  theory  of,  24 

Mercury  vapor  arc,  photograph- 
ing by,  273 
Miniature  camera,  23 
Motion-pictures,  artistic  value  of, 
290 

Oil  and  bromoil,  advantages  and 
disadvantages,  142 
best  type  of  negative, 
216,  225 

bromoil  bleacher,  for- 
mula, 226 
brushes,  213 

care  of,  213,  224 
chief  value,  229 
continuing  action  of 
light,  216 

contrast,  variations  of, 
142,  214,  215,  217,  221, 
223,  224 
decreasing,  222 
inking,  for  fine  texture, 
221 

for  transfer,  227 
hopping,  220,  221 
inking  board,  214 
keeping  qualities  of 
paper,  215,  216 
papers  for  transferring, 
227 


Oil  and  bromoil,  quick-drying 
sensitizer,  215 
safe-edge,  216 
sensitizing  by  immersion, 
212,  214 
theory,  211 

Paget  process,  256 

avoidance  of  parallax,  262 
luminosity  of  results,  262 
power  of  duplication,  262 
Palladium  paper,  296 
Permanence,  of  bromide  prints, 
affected  by  toning,  125,  127 
of  intensified  negatives,  104 
of  mercury-developed  plati- 
num prints,  150 
of  prints,  133 

Persistence  of  vision,  278 
Pin-hole,  48 

Photogravure,  advantages  and 
disadvantages,  143 
dabber,  242 

etching  baths,  strength  of, 
240 

to  make,  240 
finishing  inks,  245 
graining  the  plate,  233,  235 
for  re-etching,  245 
liquid  ground,  236 
multiple  printing,  247 
rapid  drying  of  resist,  238 
re-etching,  245 
theory,  231 
tissues  for  resist,  237 
Plates,  anti-screen,  60 
backed,  see  halation 
bromide  paper  instead  of 
plates,  74,  120 
double-coated,  see  halation 
isochromatic,  59 
non-halation,  see  halation 
ordinary,  57 

or  films,  relative  advantages, 
74 


300 


INDEX 


Plates,  orthochromatic,  59 
panchromatic,  59 
Platinum,  advantages  and  dis- 
advantages, 138 
comet  marks,  154 
contrast,  variations  of,  138, 
139,  148,  156,  159 
development  marks,  147 
hand  made,  formulae,  156 
keeping  qualities,  144,  152 
multiple  printing,  159 
old  paper,  152 
papers  for  sensitizing,  155 
saving  waste,  154 
sensitizing  tissues,  159 
sizing  for  multiple  printing, 
158 

use  of  glycerine  in  developer, 
139,  149,  154 
Port-Land  lens,  38 
Printing  frames,  97 

Quick-drying  sensitizer,  for  car- 
bon, 163 
for  oil,  215 

Ray-filter,  the,  60,  65 
exposures  with,  67 
results  without,  landscape,  62 
portraiture,  63 
selective  filters,  66 
Reduction,  105 

ammonium  persulphate  re- 
ducer, 107 

Farmer’s  reducer,  106 
for  correcting  faults  in  ex- 
posure, 82 

potassium  permanganate  re- 
ducer, 107 
Reflex  camera,  21 
Refraction  of  light,  see  light 
Refractive  index,  26 
Rendering  of  gradations,  in 
carbon,  139 
in  gum,  141 


Rendering  of  gradations,  in 
gum-platinum,  141 
in  oil  and  bromoil,  142 
in  photogravure,  143 
in  platinum,  138,  139 
in  the  ideal  medium,  134 
Retouching  on  back  of  plate,  110 
on  front  of  plate,  108 
Rising  front,  18 
Rotating  back,  19 

Sensuous  appeal  of  photography, 
254 

Sepia  tones  on  bromide  paper,  127 
Shutters,  93 
Smith  lens,  38 
Soft  focus  lens,  see  lens 
Spectrum,  the,  57 
Spherical  aberration,  31 
Spirit  sensitizer,  for  carbon,  163 
for  oil,  215 
Struss  lens,  31,  38,  39 
Studio  camera,  22 
Swing-back,  18 

Tank  development,  87 
Test  chart  (color),  61 
Texture,  of  carbon,  140,  167 
of  gum,  140,  141 
of  oil  and  bromoil,  142,  221, 
230 

of  oil  and  bromoil  transfer, 
228 

of  photogravure,  143 
of  platinum,  138,  139,  155 
of  the  ideal  medium,  134 
Three-color  gum,  advantages,  265 
enlarged  negatives  for 
three-color  gum,  269 
filters,  267 
lens,  267 
pigments,  269 
printing  from  Hess-Ives 
negatives,  268 

Toning,  bromide  prints,  127 
motion-picture  film,  288 

301 


INDEX 


Transfer  paper,  for  carbon,  166 
for  oil  and  bromoil,  227 
Traversing  (sliding)  front,  18 
Tray  development,  84,  86 
Trays,  95 

Tripod  for  motion-picture  cam- 
era, 284 

Values,  relative,  dependent  on 
exposure,  78 
in  landscape,  62,  63 
in  portraiture,  63 
modifications  of,  in  car- 
bon, 139,  173 
in  gum,  140,  192 
in  gum  - platinum, 

141,  207 

in  oil  and  bromoil, 

142,  220,  223,  229 


Values,  relative,  modifications  of, 
in  photogravure, 
143,  237,  246, 247 
in  platinum,  138 
in  the  negative,  by 
intensification, 
102 

by  reduction,  105 
by  hand  work, 
108,  110,  120 
Varnishing  prints,  bromide,  129 
platinum,  153 
Verito  lens,  38 
View  camera,  22 
Visual  luminosity,  57 

Washing  boxes,  96 
Wave  length  of  light,  see  light 
Wave  theory  of  light,  see  light 
Welsbach  light,  photographing 
by,  274 


GETTY  RESEARCH  INSTITUTE 


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